Chevrolet K5 Blazer
1973–91

Factory gearing, tires, angles and brakes for the K5 Blazer, 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

106.5 in wheelbase · 33.5 in front · 44.5 in rear overhang

Axle ratio3.07–4.11Factory, by trim

Crawl ratio66.5:1Best trim: 1988-91 350 TBI V8, NP241

Angles36 · 19 · 23°Approach, breakover, departure

Clearance7 in6.9 to 7 in by trim

Highway mpg16EPA, 14 with the manual

Trims

5 we have figures for

Trim	Tire	Transmission	Axle	Angles	Clearance	Open
1973-80 350 V8, 4-speed, NP205 (E78-15B tires)	26.6	4-speed manual	3.07 / 3.73 / 4.11	36 · 19 · 23	7.0 in	Use →
1973-79 350 V8, Turbo Hydra-matic, NP203 full-time (E78-15B tires)	26.6	3-speed automatic	3.07 / 3.73 / 4.11	36 · 19 · 23	7.0 in	Use →
1973-80 with 10.00-16.5 flotation option (10.00-16.5C tires)	31.0	4-speed manual, 3-speed automatic	3.73 / 4.11	36^* · 19^* · 23^*	7.0 in	Use →
1981-87 350 V8, NP208	P235/75R15	4-speed manual, 3-speed automatic, 4-speed automatic	3.08 / 3.42 / 3.73	24 · 22 · 26	6.9 in	Use →
1988-91 350 TBI V8, NP241	P235/75R15	4-speed manual, 4-speed automatic	3.42 / 3.73	24^* · 22^* · 26^*	6.9 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: 106.5 in
Front overhang: 33.5 in
Rear overhang: 44.5 in
Height: 72 in
Body: SUV
Stock tires: 26.6, 31.0, P235/75R15

Transmissions and low range

4-speed manual (SM465 / CH465): 6.55 · 3.58 · 1.7 · 1
3-speed automatic (Turbo Hydra-matic 350): 2.52 · 1.52 · 1
4-speed automatic (700R4 / 4L60): 3.06 · 1.63 · 1 · 0.7
Low range, np205: 1.96:1
Low range, np203: 2.01:1
Low range, np208: 2.61:1
Low range, np241: 2.72:1
Low range, dana20: 2.03:1

Axles

Front: Dana 44 (to about 1980), then GM 10-bolt 8.5 in
Rear: GM 12-bolt 8.875 in (to about 1980-81), then GM 10-bolt 8.5 in
3.07 ratio: 1973-80 350 V8, 4-speed, NP205 (E78-15B tires), 1973-79 350 V8, Turbo Hydra-matic, NP203 full-time (E78-15B tires)
3.08 ratio: 1981-87 350 V8, NP208
3.42 ratio: 1981-87 350 V8, NP208, 1988-91 350 TBI V8, NP241
3.73 ratio: 1973-80 350 V8, 4-speed, NP205 (E78-15B tires), 1973-79 350 V8, Turbo Hydra-matic, NP203 full-time (E78-15B tires), 1973-80 with 10.00-16.5 flotation option (10.00-16.5C tires), 1981-87 350 V8, NP208, 1988-91 350 TBI V8, NP241
4.11 ratio: 1973-80 350 V8, 4-speed, NP205 (E78-15B tires), 1973-79 350 V8, Turbo Hydra-matic, NP203 full-time (E78-15B tires), 1973-80 with 10.00-16.5 flotation option (10.00-16.5C tires)
Ratios made for it: 3.73 · 4.1 · 4.56 · 4.88 · 5.13 · 5.38

Brakes

Front rotor: 11.87 in, 301 mm
Front caliper piston: 75.0 mm
Rear drum: 11.15 in, 283 mm
Rear: drum (11.15 x 2.75 in)

Suspension

Front: solid axle on leaf springs
Rear: leaf springs, solid axle
Rear layout: Leaf springs

Fuel economy

EPA highway, automatic: 16 mpg
EPA highway, manual: 14 mpg
Rated years: 1984–1991, 4WD

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 K5 Blazer sees how it does on their tires and lift.

Front 5

Chassis Unlimited 1973-1991 CHEVY/GM Front Diablo Winch Bumper$1,611 · winch ready
Chassis Unlimited 1973-1991 CHEVY/GM Front Octane Winch Bumper$1,402 · winch ready
Iron Bull Bumpers 1973-1980 Chevrolet K5 Blazer Front Bumper$1,700 · winch ready
Iron Bull Bumpers 1981-1991 Chevrolet K5 Blazer Front Bumper$1,700
TrailReady 10100B Chevy Silverado 1500 1981-1988 Extreme Duty Front Bumper Winch Ready Base$3,654 · winch ready

Rear 3

Chassis Unlimited 1973-1991 CHEVY/GM Octane Dual Swing Out Rear Bumper$3,254
Chassis Unlimited 1973-1991 CHEVY/GM Octane Rear Bumper$1,402
Iron Bull Bumpers 1973-1991 Chevrolet K5 Blazer Rear Bumper$1,550 · winch ready

Every calculator, set up for the K5 Blazer

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 K5 Blazer ranks against every stock truck.See where it ranks

Source: auto-brochures.com. Check which axles you have before ordering: 1970s Dana 44/12-bolt vs 1980s 10-bolt 8.5 front and rear; each has a carrier break (Dana 44 at 3.73/3.92, 12-bolt at 3.73/3.90, 10-bolt 8.5 between low and high ratio carriers).

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 K5 Blazer1973–91