1st Gen K5 Blazer & Jimmy biggest tire size: stock and lifted
The biggest tire owners run on a Chevrolet K5 Blazer (1st generation) at every lift height, with the trimming it takes, the wheel specs you need and the lift kits that get you there.
On a 67-72 Chevy Trucks thread about a stock 1972 Blazer, several owners run 33x12.50s on 15x8 wheels. Others call 32x11.50 the limit if the springs have sagged. One owner found 33x14.50s rubbed the springs, so width matters as much as height. On CK5, a member calls 33s about 2 inches bigger than stock 31s, fine for a while on the road but likely to hit off-road.
Biggest 1st Gen K5 Blazer & Jimmy tire at every lift
| LIFT | BIGGEST TIRE | WHAT IT TAKES |
|---|---|---|
| Stock | 33x12.50R15 | On 15x8 wheels with healthy springs. Owners say 32x11.50 is the limit on sagging springs, and 33x14.50s rubbed the springs on one truck. Expect contact off-road at full stuff. |
| 4 in | 35 in | One CK5 owner ran 35s on a 4 in lift on the highway, but warns that 4 in isn't enough off-road once the axle articulates. |
| 5 in | 33 in | A 5 in Tuff Country lift runs 33s with no rubbing. The owner thought 35s would fit but would need gears deeper than the stock 3.73s. |
1st Gen K5 Blazer & Jimmy wheel and tire specs
| Factory tire sizes | 7.35-15 (1969 standard) · E78-15B (1971 standard, 4x4) · Options to 10.00-16.5 (1969–71 spec sheets) |
|---|---|
| Bolt pattern | 6x139.7 (6x5.5") |
Lift kits, wheels and tires for the 1st Gen K5 Blazer & Jimmy
Fresh springs fix sagging 50-year-old leaves and clear 33s or 35s. Offroad Design builds custom-arc springs specifically for 1969–72 GM trucks.
Do you need to re-gear?
The 1971 spec sheet lists 3.73 gears as standard on the 4x4, with 3.07 optional on V8 trucks. Owners on CK5 warn that 33s feel big with 3.08s. Offroad Design generally recommends gearing a lifted truck deeper to keep the engine in its useful rev range.
Fitment comes from owners and specialists; wheel width, offset, trimming and bump stops change what fits. Check clearance at full lock and full flex before you buy. Some links are affiliate links.