Age-Old QuestionI am wondering what the biggest size tire is that I could run without grenading the axles on my 1967 Jeep CJ-5. Currently the Jeep is sitting on small, narrow tires. I have a set of 33x12.50R15 Hankook MTs that I want to put on it for stability reasons. I know I will need to lift it and buy new rims. How much lift and offset should I have on my Jeep to get them to fit, without trimming fenders? The Jeep is in good condition with the original Buick V-6 in it, so I want to keep the body as stock as possible. I live in Kansas, so the Jeep will be doing mostly dirt road cruising, with the occasional mud to drive through.
We get questions like this a lot, and there is usually not an easy answer. There aren’t really any formulas to follow. Every vehicle is different, and much depends on the intended uses. You could slap some 40-inch tires on the Jeep if it was only ever going to see parade duty and you didn’t mind not being able to turn, while you could easily grenade one or both axles with the stock tires just by adding a locker or two and a heavy foot.
Your Jeep most likely has a closed-knuckle Dana 27 front and an offset, coarse-spline Dana 44 rear. Both are considered fairly marginal, though the rear can be beefed up significantly with a variety of upgrades, such as a full-float conversion from ATV Manufacturing (hermtheoverdriveguy.com). We’ve been to Kansas and noted, to put it politely, that there’s not much elevation change. Assuming mostly flat dirt roads with the occasional mud hole, stock engine, and open differentials, the axles should hold up to 33s just fine unless you plan on doing brake stands and side-stepping the clutch at full throttle.
You are going to need 3 to 4 inches of lift in order to clear 33s on your CJ-5. A few companies still make lift kits for the early CJs, including Rusty’s Off-Road (rustysoffroad.com), Skyjacker (skyjacker.com), and Superlift (superlift.com). Standard 15x8 wheels with 3 1/2 inches of backspacing should work just fine. The suspension should make an improvement in ride over the stock stuff, and the shocks could probably stand to be replaced anyway.
Note that the old Ross cam and lever steering system isn’t going to like the lift very much, and the rear driveline may become unhappy without a fresh set of U-joints. If the steering bothers you after the lift, a variety of conversion kits are available to convert the Jeep to the later and more common Saginaw steering system.