Chevrolet C/K 1500
GMT400, 1988–98

Factory gearing, tires, angles and brakes for the C/K 1500, and what the usual upgrades do to it. Every number is from the maker's own figures unless the calculators say otherwise. A few figures here are still waiting on a factory document; the calculators mark them.

Use this truck in the calculators

117.5 in wheelbase · 34.9 in front · 47.27 in rear overhang

Axle ratio3.42–4.1Factory, by trim

Crawl ratio73.0:1Best trim: 1991 K2500

Angles25 · 19 · 25°Approach, breakover, departure

Clearance9.2 in7.7 to 9.2 in by trim

Highway mpg17EPA

Trims

6 we have figures for

Trim	Tire	Transmission	Axle	Angles	Clearance	Open
1991 K1500 Regular Cab	LT245/75R16	Hydra-matic 4L60-E 4-speed automatic	—	25^* · 19^* · 25^*	8.6 in	Use →
1995 K1500 Regular Cab	LT225/75R16	NV3500 5-speed manual, full-size wide ratio, Hydra-matic 4L60-E 4-speed automatic	3.42 / 3.73	22 · 19^* · 28	8.6 in	Use →
1995 K1500 Extended Cab	LT245/75R16	NV3500 5-speed manual, full-size wide ratio, Hydra-matic 4L60-E 4-speed automatic	3.42 / 3.73	25 · 19 · 25	9.2 in	Use →
K1500 Z71 Off-Road Package	LT265/75R16	NV3500 5-speed manual, full-size wide ratio, Hydra-matic 4L60-E 4-speed automatic	3.42 / 3.73	26 · 20 · 25	8.6 in^*	Use →
1991 K2500	LT245/75R16	Muncie SM465 4-speed manual, Hydra-matic 4L60-E 4-speed automatic	3.73 / 4.1	25^* · 19^* · 25^*	7.7 in	Use →
K2500 HD (C6P) / K3500	LT245/75R16	NV4500 5-speed manual, Hydra-matic 4L80-E 4-speed automatic	3.73 / 4.1	35 · 21 · 23	7.8 in	Use →

* The maker doesn’t publish this figure for that trim, so it shows the closest trim’s (same tire where we have one), or a close relative’s that shares the same body or front end. Hover the star to see which.

Size

Wheelbase: 117.5 in to 141.5 in
Front overhang: 34.9 in
Rear overhang: 47.27 in
Height: 76 in
Body: Pickup
Stock tires: LT225/75R16, LT245/75R16, LT265/75R16

Transmissions and low range

NV3500 5-speed manual, full-size wide ratio: 4.02 · 2.32 · 1.4 · 1 · 0.73
Hydra-matic 4L60-E 4-speed automatic: 3.059 · 1.625 · 1 · 0.696
Hydra-matic 4L80-E 4-speed automatic (HD): 2.482 · 1.482 · 1 · 0.75
NV4500 5-speed manual (GM, 1994+): 5.61 · 3.44 · 1.71 · 1 · 0.73
NV4500 5-speed manual (GM, 1993): 6.34 · 3.44 · 1.71 · 1 · 0.73
Muncie SM465 4-speed manual (granny low): 6.55 · 3.58 · 1.7 · 1
Low range, np241: 2.72:1

Axles

Front: GM 8.25 in IFS (K1500); 9.25 in IFS (K2500/K3500)
Rear: GM 8.5 in 10-bolt (K1500); 9.5 in 14-bolt semi-float or 10.5 in 14-bolt full-float (K2500/K3500)
3.42 ratio: 1995 K1500 Regular Cab, 1995 K1500 Extended Cab, K1500 Z71 Off-Road Package
3.73 ratio: 1995 K1500 Regular Cab, 1995 K1500 Extended Cab, K1500 Z71 Off-Road Package, 1991 K2500, K2500 HD (C6P) / K3500
4.1 ratio: 1991 K2500, K2500 HD (C6P) / K3500
Ratios made for it: 3.73 · 4.1 · 4.56 · 4.88

Brakes

Front rotor: 11.61 in, 295 mm
Front caliper piston: 75.0 mm
Rear drum: 10.00 in, 254 mm
Rear: drum (10 x 2.25 in)

Suspension

Front: 4x4: double wishbone IFS, torsion bars
Rear: leaf springs, solid axle
Rear layout: Leaf springs

Fuel economy

EPA highway, automatic: 17 mpg
EPA highway, manual: 17 mpg
Rated years: 1989–1998, 4WD

Frame

Rail top at the rear axle: 29.1 in off the ground
Measured on: P245/75R16

Brake upgrades

What bigger tires need →

8-lug 8600 GVW front caliper swap (Raybestos FRC4413C / FRC4414C)+14% brake torque11.6 → 11.6 in rotor · 1-pistonReman calipers only; owners pair it with a matching master cylinder and stainless lines.

Aftermarket bumpers

8 listed

Makers almost never publish angles, bottom heights or how far a bumper tucks, so these fill in as owners measure them. Measured yours? Add it on the rig page and every owner of this C/K 1500 sees how it does on their tires and lift.

Front 6

Ali Arc Classic Chevy Silverado 1500 1988-1998 Front Bumper CHB200$2,669
ARB 3462030 GMC Sierra 1500 1988-1998 Deluxe Front Bumper Winch Ready with Grille Guard, Black Powder Coat Finish$2,429 · winch ready
Hammerhead 600-56-0185 Chevy Silverado 1500 1988-1998 Front Bumper Winch Ready No Brushguard$2,056 · winch ready
Iron Bull Bumpers 1988-1998 Chevrolet Silverado 1500 Front Bumper$1,700
Ranch Hand Legend Series Front Bumper FBC881BLR220 lb · $2,023
TrailReady 10200B Chevy Silverado 1500 1988-1999 Extreme Duty Front Bumper Winch Ready Base$3,654 · winch ready

Rear 2

Hammerhead 600-56-0686 Chevy Silverado 1500 1988-1998 Rear Bumper Flush Mount Step Side$1,764
Iron Bull Bumpers 1988-1998 Chevrolet Silverado 1500 Rear Bumper$1,550 · winch ready

Every calculator, set up for the C/K 1500

Tire sizeBigger tires: speedo, clearance, angles and brakes.Compare tires RegearHighway RPM on every ratio and mpg.Pick your gears Crawl ratioHow slow it creeps, against other trucks.Work out crawl SpeedometerWhat it really reads on new tires.Fix your speedo LinksAnti-squat and what a lift does to it.Check your links Your rigBuild sheet and measured angles.Start a build sheet LeaderboardsWhere the C/K 1500 ranks against every stock truck.See where it ranks

Source: auto-brochures.com. GM 8.25 IFS and 8.5 10-bolt use one carrier for most ratios, but 4.56+ in the 8.5 needs the 3-series carrier; check before ordering.

Use at your own risk. These calculators are here to help you plan and to inform your decisions, not to sign off on a build. Many numbers are estimates worked out from factory figures, and some factory figures are not yet confirmed. Check every number against your own truck, its manuals and a qualified shop before you buy parts, cut, weld, lift, regear or drive on it. Long Range Desert Tools is not liable for anything you do based on these calculators or their results. The full terms are in our policies.

Chevrolet C/K 1500GMT400, 1988–98