2000 CHEVY BLAZER


PRODUCT OVERVIEW:  The Chevy Blazer, with its aerodynamic
                   styling and long list of product
                   features, is a hot contender in the
                   growing sport/utility market, which is
                   dominated by 4x4 four-door models.
                   
                   
NEW FOR 2000:    * Locking differential added to all 4x4
                   models
                 * Tachometer has been added to all levels
                   of Blazer for 2000
                 * TiltWheel(tm) and speed control added as
                   standard
                 * Power door locks, power windows and
                   exterior heated electric remote control
                   mirrors added as standard
                 * Aluminum wheels and roof luggage
                   carrier added as standard
                 * Standard sound system on 2-door models
                   is AM/FM stereo with seek-scan,
                   cassette with search and repeat,
                   digital clock, auto tone control,
                   theft-deterrent feature and
                   speed-compensated volume
                 * Standard sound system on 4-door models
                   is AM/FM stereo with /seek-scan, CD
                   player, digital clock, auto tone
                   control, theft-deterrent feature and
                   speed-compensated volume
                 * Interior overhead deluxe roof console
                   and redundant steering wheel audio
                   controls included with LT Trailblazer
                 * High-back reclining bucket seats are
                   standard seating on 4-door model
                 * Vortec 4300 V6 engine enhancements
                 * Air bag diagnostic module enhancements
                 * Anti-lock brake system controller
                   enhancements
                 * Child safety seat top tether anchor
                   added to all Blazer models
                 * Two new exterior colours - Space Blue
                   Metallic (2-door) and Red Tint Coat
                   (4-door)
                 * Two discontinued exterior colours
                   (Medium Beige Mystique Metallic and
                   Dark Copper Metallic)
                   
                   
MODELS:            Blazer LS
                   Blazer LT
                   
                   
VEHICLE CLASS:     Small Utility
                   
                   
ASSEMBLY           Linden, New Jersey; Moraine, Ohio
LOCATIONS:
                   
                   
CUSTOMER PROFILE:  The Chevy Blazer is targeted at
                   well-educated adults (30-54) in
                   professional/white collar positions.
                   They look for a vehicle that gives them
                   an "edge on life" and an advantage over
                   the challenges of daily driving.  These
                   buyers frequently form an emotional
                   attachment with their vehicle and trust
                   it to be dependable and reliable,
                   regardless of road conditions.

PRODUCT MILESTONES:
                   1983 - New model introduction;
                          Insta-Trac(tm) 4x4 system
                   1986 - Electronic fuel injection for
                          optional 2.8-litre V6
                   1988 - 4.3-litre V6 with electronic
                          fuel injection and serpentine
                          belt drive introduced as an
                          option
                   1989 - Rear-wheel anti-lock brakes
                          (ABS) and electric speedometer;
                          new transfer case
                   1990 - 4.3-litre V6 standard; new
                          5-speed manual transmission with
                          overdrive
                   1991 - Introduction of 4-door model in
                          2WD or 4x4 with 4-wheel anti-lock
                          brakes (ABS)
                   1992 - 4-wheel anti-lock brakes (ABS)
                          standard for all models; optional
                          new electronic-shift transfer
                          case for 4x4 models
                   1993 - Enhanced 4.3-litre V6 with
                          central-port fuel injection
                          (horsepower jumps to 200);
                          electronic 4-speed automatic
                          transmission debuts
                   1994 - Improved corrosion protection;
                          LED centre high-mounted stop lamp
                          introduced
                   1995 - All-new exterior and interior;
                          driver-side air bag; new
                          chassis/suspension packages
                   1996 - New all-wheel-drive system
                          available; enhancements to Vortec
                          4300 SFI V6 engine and 4-speed
                          electronic automatic transmission
                          for improved driveability and
                          fuel economy
                   1997 - Four-wheel disc brakes on all
                          AWD models; available
                          Homelink® 3-channel, programmable
                          garage door opener; 4-door liftgate
                          with liftglass; and available
                          electric sunroof
                   1998 - Restyled exterior front end; new
                          instrument panel with full
                          frontal airbags; addition of
                          numerous new features; four-wheel
                          disc brakes standard
                   1999 - New active transfer case to be
                          marketed as Autotrac(tm) includes
                          2HI 4HI, 4LO, and auto 4x4 and
                          neutral, available as an upgrade
                          over standard electronic shift
                          transfer case; available power
                          passenger seat and memory seat
                          functions for driver seat; 6-disc
                          CD changer, Bose® premium sound
                          system and steering wheel radio
                          controls available; new family of
                          outside mirrors with features
                          including power, heated, and
                          electrochromic; transmission
                          shift preference select changes
                          the transmission shift schedule
                          to optimize trailering
                          performance for automatic
                          transmission-equipped vehicles
                   2000 - Mechanical enhancements and
                          increased content


                                LS \   LS  \ LT   \  LT
                                all \ 2-door\ cloth\leather
EXTERIOR FEATURES              models\       \4-door\4-door

Bumpers            Front and rear, body colour   S  S  -  -
                   with matching air dam
                                                           
                   Front, chrome with rub        -  -  S  S
                   strip, rear body colour
                                                           
Fog Lamps          Fog lights (not available on  -  O  O  S
                   4x4 2-door models)
                                                           
Glass              Solar-Ray(tm), deep tinted    S  -  -  -
                   rear quarter with light tint
                   on other windows
                                                           
                   Solar-Ray(tm), deep tinted    -  S  S  S
                   rear quarter and rear glass
                   with light tint on all other
                   windows
                                                           
Grille             Gray with chrome centre bar   S  S  -  -
                                                           
                   Body colour with chrome       -  -  S  S
                   centre bar
                                                           
Liftgate           With integral liftglass       S  -  S  S
                   (4-door models only)
                                                           
Liftglass/Dropgate 2-door models                 S  S  -  -
                                                           
                   4-door models                 O  -  O  O
                                                           
Luggage Carrier    Roof-mounted                  S  S  S  S
                                                           
Mirrors            Fold-away, power remote       S  S  -  -
                   control, heated
                                                           
                   Fold-away, power remote       -  O  S  S
                   control, heated, driver-side
                   includes auto-dimming
                   electrochromic
                                                           
Mouldings          Black lower bodyside, with    -  -  S  S
                   chrome insert
                                                           
Skid Plates        Off-Road (4x4)                O  O  O  O
                                                           
Spare Tire/Wheel   2-door, compact spare tire    S  S  -  -
                   with steel wheel mounted
                   inside with cover
                                                           
                   2-door 4x4s, full-size spare  O  O  -  -
                   tire mounted on outside rear
                   carrier with cover
                                                           
                   4-door, full-size spare tire  S  -  S  S
                   with underbody
                   winch-operated carrier
                                                           
Sunroof            Power, tilt and sliding       O  O  O  O
                   glass panel
                                                           
Tow Hooks          Two front (4x4)               S  S  S  S
                                                           
Wheels             15"x 7"                       S  S  S  S
                                                           
Window             Swing-out rear quarter        S  S  -  -
                   (2-door models)
                                                           
Wiring Harness     Trailer, 6-lead               S  S  S  S
                                                           
S - Standard Equipment.   O - Optional Equipment.


                                 LS \  LS  \   LT \  LT
                                 all \2-door\ cloth\leather
INTERIOR FEATURES              models \      \4-door\4-door

Air Conditioning   Air conditioning, front       S  S  S  -
                                                           
                   Front, electronic climate     -  -  -  S
                   control
                                                           
Cargo Tie Downs    Four                          S  S  S  S
                                                           
Console            Front floor, includes a       S  S  S  S
                   storage tray, cupholders,
                   coin holders and storage
                   compartment (shift lever is
                   steering column-mounted)
                                                           
                   Overhead with electronic      S  S  S  -
                   compass and outside
                   temperature readouts
                   (standard on LS 4-door only)
                                                           
                   Overhead, deluxe, includes a  -  O  O  S
                   universal 3-channel
                   programmable transmitter
                   plus enhanced electronic
                   display with trip computer,
                   electronic compass and
                   outside temperature readouts
                                                           
Defogger and
Wiper/Washer       Rear window, intermittent     S  S  S  S

                                                           
Door Trim Panels   Colour-keyed plastic with     S  -  -  -
                   vinyl and cloth, integral
                   armrests with switches for
                   exterior mirrors, windows
                   and locks, storage pockets
                                                           
                   Colour-keyed cloth upper      -  S  S  -
                   inserts with carpeted lower
                   inserts, padded integral
                   armrests with switches for
                   exterior mirrors, windows
                   and locks, storage pockets
                                                           
                   Colour-keyed leather inserts  -  -  -  S
                   with carpeted lower inserts;
                   padded integral armrests
                   with switches for exterior
                   mirrors, windows and locks,
                   storage pockets
                                                           
Floor Coverings    Colour-keyed carpeting,       S  S  S  S
                   carpeted front and rear
                   floor mats
                                                           
Heater/Defogger    Heater/vent and side window   S  S  S  -
                   defogger system with rear
                   seat heat ducts
                                                           
                   Same as above plus automatic  -  -  -  S
                   electronic climate control
                                                           
Instrumentation    Full analogue design with     S  S  S  S
                   tachometer
                                                           
Mirror             Inside, auto-dimming          -  -  S  S
                   electrochromic
                                                           
Power Features     Power door locks              S  S  S  S
                                                           
                   Power outlets, two            -  S  S  S
                   auxiliary, 12-volt
                                                           
                   Power windows with lockout    S  S  S  S
                   feature
                                                           
Seats              Front, reclining driver and   S  S  -  -
(2-Door Models)    front passenger, high-back
                   buckets with folding
                   seatbacks, manual seat-back
                   recliners and easy-entry
                   feature on passenger side
                                                           
                   Rear, 50/50 two-passenger     S  S  -  -
                   split-folding rear seat with
                   outboard headrests
                                                           
                   Power, 6-way driver-seat      O  O  -  -
                   adjuster
                                                           
Seats              Front, reclining driver and   S  -  -  -
(4-Door Models)    front passenger, high-back
                   buckets with folding
                   seatbacks and manual
                   seat-back recliners
                                                           
                   Front, reclining driver and   -  -  S  -
                   front passenger bucket seats
                   with manual two-way
                   headrests and power lumbar
                   adjusters with Premium cloth
                   trim
                                                           
                   Front, custom leather (on     -  -  -  S
                   seating surfaces), reclining
                   driver and passenger bucket
                   seat with manual two-way
                   headrests, 6-way power
                   driver and front seat
                   adjusters, power seatback
                   recliners and power lumbar
                   adjusters, driver-side
                   includes two-position memory
                   feature
                                                           
                   60/40 reclining front         O  -  -  -
                   split-bench, deletes
                   standard floor console
                                                           
                   Rear, 60/40 three-passenger   S  -  S  S
                   rear folding split-bench
                   with folding outboard
                   headrests, leather seating
                   surfaces with LT
                                                           
                   Power, 6-way driver seat      O  -  S  -
                   adjusters
                                                           
                   8-way driver and              -  -  O  S
                   passenger-seat adjuster
                   (6-way seat with 2-way power
                   seat-back recliners),
                   driver-side includes a  
                   2-position memory feature                                                           
                   Heated front seats            -  -  -  O
                                                           
Security Shade     Cargo (not available on       -  O  S  S
                   2-door 2WD models)
                                                           
Speed Control      Speed control                 S  S  S  S
                                                           
Steering           Tilt-Wheel(tm)                S  S  S  S
                                                           
Steering Wheel     Leather-wrapped, 4-spoke,     -  S  S  S
                   Black
                                                           
Sunshades          LH and RH padded; RH with     S  -  -  -
                   vanity mirror
                                                           
                   LH and RH padded,             -  S  S  S
                   illuminated vanity mirror
                                                           
Tailgate           Liftglass/Dropgate with       S  S  O  O
                   power release (standard on
                   LS 2-door only)
                                                           
                   Liftgate/Liftglass with       S  -  S  S
                   power release (standard on
                   LS 4-door only)
                                                           
Trunk              Cargo convenience net         -  S  S  S
                                                           
S - Standard Equipment.   O - Optional Equipment.

                                 LS \  LS  \  LT  \  LT
                                  all\2-door\cloth \leather
SOUND SYSTEMS                   models\      \4-door\4-door

   All Blazer sound systems include an electronically
   tuned Delco AM/FM stereo with seek up/down, scan,
   digital clock and 6-speaker sound system:
                                                           
                   AM/FM stereo with cassette    S  -  O  -
                   tape player, Auto Tone       
                   Control, Speed Compensated   
                   Volume control and
                   TheftLock(tm) (standard on
                   2-door LS and optional on
                   4-door LS)
                                                           
                   Same as above except a CD     S  S  S  -
                   player replaces the cassette
                   tape player (standard on     
                   4-door LS and optional on
                   2-door LS)
                                                           
                   Same as above except both     O  O  O  S
                   cassette tape and CD players
                   are included
                                                           
                   Six-disc remote CD changer    O  -  O  O
                   located in the centre
                   console (4-door models)
                                                           
                   Bose(R)Premium sound system   O  -  O  O
                   (4 door models)
                                                           
                   Steering wheel sound system   O  O  O  O
                   controls
                                                           
S - Standard Equipment.   O - Optional Equipment.

                                 LS \  LS  \  LT  \  LT
                                 all \2-door\ cloth\leather
MECHANICAL FEATURES             models\      \4-door\4-door

Block Heater       Engine block heater           S  S  S  S
                                                           
Brakes             4-wheel anti-lock braking     S  S  S  S
                   system (ABS)
                                                           
Differential       Locking rear axle, 4x4        S  S  S  S
                   models
                                                           
                   2WD models                    O  O  O  O
                                                           
Engine             Vortec 4300 V6 with SFI       S  S  S  S
                                                           
Exhaust System     Aluminized stainless steel    S  S  S  S
                                                           
Oil Cooler         Engine oil cooler             S  S  S  S
                                                           
Steering           Integral power, variable      S  S  S  S
                   ratio
                                                           
Suspension         Premium Ride, high pressure   S  -  S  S
                   gas monotube shock
                   absorbers, front and rear
                   stabilizer bars (4-door
                   only)
                                                           
                   Touring, provides a firm      S  S  O  O
                   ride with stiffer springs
                   than Premium Ride Suspension
                   (2-door)
                                                           
                   4-door, same as above         O  S  O  O
                                                           
                   Off-road, provides a very     O  O  -  -
                   firm ride with stiffer
                   springs, stabilizer bars,
                   jounce bumpers and larger
                   body mounts; includes
                   P235/75R-15 On-Off Road
                   tires with a full-size spare
                   mounted on an outside
                   carrier (2-door 4x4 models
                   only)
                                                           
Tires              P235/70R-15 all-season        S  S  S  S
                   blackwall with compact spare
                                                           
                   P235/75R-15 On-Off Road       O  O  O  O
                   white-lettered with
                   full-size spare (4x4 models)
                                                           
TrailBlazer        Provides all the features of  -  -  -  O
Package            the LT Leather-trimmed
                   Blazer with the following
                   substitutions or additions:

                   * Colour-keyed bodyside and
                     rocker panel mouldings

                   * Styled aluminum wheels
                     with gold accents

                   * Deluxe overhead console
                     with universal Homelink(R)
                     3-channel, programmable
                     transmitter, enhanced
                     electronic display with trip
                     computer, electronic compass
                     and outside temperature
                     readouts

                   * OnStar® Communications
                     System

                   * Two-tone leather with
                     TrailBlazer embroidered on
                     the door trim panels, padded
                     integral armrests with
                     electric outside mirror and
                     door lock switches

                   * Steering wheel sound
                     system controls

                   * Custom leather on seating
                     surfaces with exclusive
                     TrailBlazer embroideries on
                     the headrests and a front
                     floor shifter console
                     between the front bucket
                     seats

                   * Autotrac(tm), electronic 4x4
                     system which adds an
                     automatic 4-wheel drive mode
                     for driver convenience

                   * Touring suspension chassis           
                     package

"ZR2" Wide Stance   Includes serious off-road    -  -  -  O
Sport Performance   capability to the 2-door
Package             LS Blazer with the
                    following modifications:

                   * Special front and rear
                     quarter panels with
                     extra-wide Dark Gray fender
                     flares

                   * Full-size spare tire on an    
                     outside, rear-mounted
                     carrier

                   * Underbody shield package
                     protecting the transfer
                     case, front differential,
                     fuel tank and steering
                     linkage

                   * Unique, revised frame for
                     a wider track

                   * Strengthened front
                     differential gears and drive
                     axles

                   * Special rear axle with a
                     216 mm (8.5 in.) ring gear,
                     large wheel bearings and
                     longer, larger diameter axle
                     shafts

                   * Revised multi-leaf rear
                     spring suspension with an
                     added rear axle track bar

                   * 46 mm gas pressurized shock
                     absorbers and 33 mm front
                     stabilizer bar

                   * 31 x 10.5 R-15 On-Off Road
                     tires, front, rear and spare
                                                           
Transmission       4-speed automatic with        S  S  S  S
                   overdrive and 2nd-gear start
                   feature
                                                           
                   5-speed manual with           O  O  -  -
                   overdrive (not available
                   with trailering special
                   equipment or 4-door models)
                                                           
Transfer Case      Part-time, 2-speed, electric  S  S  S  S
                   shift with 2HI, 4HI and 4LO
                   (4x4 models)
                                                           
                   Autotra(tm), adds automatic   O  O  O  O
                   4-wheel drive function
                   (4x4 models)

S - Standard Equipment.   O - Optional Equipment.

                                 LS \  LS  \  LT  \  LT
                                  all\2-door\cloth \leather
SAFETY AND SECURITY             models\      \4-door\4-door

Air Bags           Next Generation, driver- and  S  S  S  S
                   front-passenger, frontal
                                                           
BTSI               Brake/transmission shift      S  S  S  S
                   interlock
                                                           
Brakes             Power, 4-wheel disc           S  S  S  S
                                                           
Child Safety Seat  Tether anchors                S  S  S  S
                                                           
Door Beams         Side-guard door beams         S  S  S  S
                                                           
Door Locks         Rear door, child-security     S  -  S  S
                   (4door)
                                                           
Keyless Entry      2-door, remote (includes      -  S  S  S
                   theft-deterrent alarm
                   system)
                                                           
                   4-door, remote (includes      S  S  S  S
                   theft-deterrent alarm
                   system)
                                                           
Lights             Daytime running lights with   S  S  S  S
                   flash-to-pass, automatic
                   light control
                                                           
Roadside Service   24-hour Roadside Assistance   S  S  S  S
                   Program
                                                           
Safety Belts       Front seat, height-           S  -  S  S
                   adjustable (4-door)
                                                           
                   Rear seat child shoulder      S  -  S  S
                   belt comfort guides (4-door)
                                                           
Theft-Deterrent    PASSLock(tm) theft-deterrent  S  S  S  S
                   system

S - Standard Equipment.  O - Optional Equipment.


TECHNICAL PRODUCT INFORMATION



FRAME   
           Welded-steel frame
                   
                   
BODY MATERIAL      Hot-dipped steel (two-sided galvanized
                   steel on strategic panels, excluding
                   roof)
                   
                   
SUSPENSION   front Independent, (coil springs 2WD; torsion
                   bar 4x4)
             rear  Semi-elliptic, 2-stage multi-leaf
                   springs
                   
                   
BRAKES             Power-assisted, front and rear disc;
                   4-wheel anti-lock (ABS)
                   
                   
STEERING           
Type               Power, variable ratio
Turns              3.38 - 2WD
                   2.97 - 4x4
Turning Diameters  34.8 ft. - 2WD (2-door)
                   36.6 ft. - 2WD (4-door)
                   35.2 ft. - 4x4 (2-door)
                   39.5 ft. - 4x4 (4-door)
                   
                   
WHEELS             15" x 7" steel
                   
TIRES              P235/70R15 all-season (standard)
                   
                   
ENGINE             Vortec 4300 SFI V6
Type               OHV, 4.3L V6
Block              Cast Iron
Cylinder Head      Cast Iron
Bore x Stroke      101.60 x 88.39 mm
                   (4.00" x 3.48")
Displacement       4300 cc (262 cu.in.)
Compression Ratio  9.2:1
Fuel               Regular, Unleaded
Fuel Induction     Sequential Central Port Fuel Injection
                   (SCPI)
Horsepower         190 hp
                   @ 4400 rpm
Torque             250 lb.-ft.
                   @ 2800 rpm
                   
                   
LAYOUT             Front engine / 2WD (rear) or 4x4
                   
                   
TRANSMISSIONS      4-Speed Electronic   5-Speed Manual with
                   Automatic with       Overdrive
                   Overdrive
Gear Ratios    1st 3.06                 3.49
               2nd 1.63                 2.16
               3rd 1.00                 1.40
               4th 0.70                 1.00
               5th ---                  0.78
Reverse            2.29                 3.55
Final Drive Ratios 3.42                 3.42
                   3.08 (optional)      3.08 (optional)
                   3.73 (optional)      3.73 (optional)
                                        
EXTERIOR DIMENSIONS
                   2WD (2-door)         2WD (4-door)
Wheelbase          2553 mm (100.5")     2718 mm (107.0")
Length             4516 mm (177.8")     4681 mm (184.3")
Width              1722 mm ( 67.8")     1722 mm ( 67.8")
Height             1648 mm ( 64.9")     1633 mm ( 64.3")
                                
                                
EXTERIOR DIMENSIONS
                   4x4 (2-door)         4x4 (4-door)
Wheelbase          2553 mm (100.5")     2718 mm (107.0")
Length             4516 mm (177.8")     4681 mm (184.3")
Width              1722 mm ( 67.8")     1722 mm ( 67.8")
Height             1638 mm ( 64.5")     1631 mm ( 64.2")
                                        
                                        
INTERIOR DIMENSIONS
                   2WD (2-door)         2WD (4-door)
Head Room          1006/ 973 mm         1006/ 973 mm
        front/rear (39.6/38.3")         (39.6/38.3")
Leg Room           1077/ 904 mm         1077/ 922 mm
        front/rear (42.4/35.6")         (42.4/36.3")
Shoulder Room      1466/1412 mm         1453/1453 mm
        front/rear (57.7/55.6")         (57.2/57.2")
Hip Room           1321/1029 mm         1321/1303 mm
        front/rear (52.0/40.5")         (52.0/51.3")
                                
                                
INTERIOR DIMENSIONS
Head Room          4x4 (2-door)         4x4 (4-door)
        front/rear
Leg Room           1006/ 973 mm         1006/ 973 mm
        front/rear (39.6/38.3")         (39.6/38.3")
Shoulder Room      1077/ 904 mm         1077/ 922 mm
       front/rear  (42.4/35.6")         (42.4/36.3")
Hip Room           1466/1412 mm         1453/1453 mm
        front/rear (57.7/55.6")         (57.2/57.2")
                   1321/1029 mm         1321/1303 mm
                   (52.0/40.5")         (52.0/51.3")
                                
                                
WEIGHTS/CAPACITIES              
                   2WD (2-door)         2WD (4-door)
Curb Weights        1595 kg              1665 kg
                   (3520 lb.)           (3670 lb.)
Fuel Capacities    72 L                 68 L
                   (15.8 gal.)          (15.0 gal.)
Passenger Seating  5/4                  6/5
Cargo Volumes:                          
with rear seat up   855 L               1056 L
                   (30.2 cu.ft.)        (37.3 cu.ft.)
with rear seat     1894 L               2098 L
down               (66.9 cu.ft.)        (74.1 cu.ft.)
Payloads (maximum)   460 kg               560 kg
                   (1015 lb.)           (1235 lb.)
GVWR (standard)     2020 kg              2200 kg
                   (4450 lb.)           (4850 lb.)
                                        
                                
WEIGHTS/CAPACITIES
                   4x4 (2-door)         4x4 (4-door)
Curb Weights       1745 kg              1835 kg
                  (3850 lb.)           (4050 lb.)
Fuel Capacities    72 L                   68 L
                  (15.8 gal.)          (15.0 gal.)
Passenger Seating  5/4                  6/5
Cargo Volumes:                          
with rear seat up    855 L               1056 L
                   (30.2 cu.ft.)        (37.3 cu.ft.)
with rear seat      1894 L               2098 L
down               (66.9 cu.ft.)        (74.1 cu.ft.)
Payloads (maximum)  480 kg (1065 lb.)    545 kg (1200 lb.)
GVWR (standard)    2270 kg (5000 lb.)   2425 kg (5350 lb.)
                                
Trailer Weights    2WD Models with      4x4 Models with
(maximum)          Automatic            Automatic
                   Transmission         Transmission
                   2220 kg.             2085 kg.
                   (4900 lb.)           (4600 lb.)
                    - 3.08 axle ratio    - 3.08 axle ratio
                   2675 kg.             2540 kg.
                   (5900 lb.)           (5600lb.)
                    - 3.42 axle ratio    - 3.42 axle ratio
                                        2540 kg.
                                        (5600 lb.)
                                         - 3.73 axle ratio