Tire size for my 90YJ

If your having problems on hills now, its gonna be worse with larger tires. Your gonna need a higher gear ratio to get max use outta your tranny. Sounds like you've got the 2.5L four banger. If so, tough luck. If you have the 4.0L six, with your setup you can go to a 31X10.50 tire with out problems (still need higher gears though). You have to go with a taller lift for tires bigger than that or they will rub on your springs and fender flares. I have 33X12.50s on my 91 Wrangler 4.0L, but I have 5" of lift and

4.10 gears. I can use fifth gear with no problem.

ive the 2.5L and 4th is too high and third is too low,

i was thinking with 32's on it it would set me right with 3rd gear without winding the motor out so bad,

johnp

You can stuff 32s in there, but you aren't gonna have any room in the wells without some kind of rubbing -- even highway bumps. They might solve the highway problem and use of 3rd gear though. With a Wrangler that old, the springs are probably shot anyway. Wrangler stock springs look almost flat, hardly any arch. If your springs look as though they're reversed arched when the vehicle weight is on them, then you need to replace them.

31's are all you can run without serious rubbing. The extra tire diameter (plus new tires with tread!) will move your speed in any gear up by about 5% to 7%. should make 3rd gear a lot more comfortable.

Yours should have the 4.10:1 axle. Chang> ive a 90 YJ, 1.5 inch spring lift 1 inch body lift,

3rd gear might work out for you, but I'm betting that you'll see problems with the others. You're going to be underpowered for those size tires with your gears on the road, much less when you get out on the trails.

You've gotten some very good advice from these guys. If you want to go with bigger tires, you need better gear ratio and more lift to get it done and make it work right.

NT

Old wives tale. At the same speed the additional hp to run bigger tires is negliable. They will change the effective gear ratio so you might need more hp (lower on thepower curve) but that is not what you said.

On FLAT ground, the only difference is any difference in rolling resistance. Big tires, light vehicle, trivial difference. On up hill, same story except you have to haul the extra pounds up the hill. Extra

10 to 20 pounds per tire adds less than 100 pounds. Half the weight of your MIL.

L.W.(ßill) Hughes III wrote:

But hot rodders who use aluminum flywheels want to ACCELERATE quickly. You original statement was that

"oversized tires will take about fifty more horsepower to turn at the same speeds"

I don't see anything in those words about ACCELERATION. You clearly said "at the same speed"

Quit spread> Or why Hot Rodders use aluminum flywheels.

I agree with RoyJ. I installed 31x10.5 on my 90YJ and regeared to

3.73. Cannot notice any difference >But hot rodders who use aluminum flywheels want to ACCELERATE quickly.

__ Arold "Al" Green

The issue with mountain bike tires versus road bike tires has more to do with compliance than weight. That is why land speed record holders used aluminum tires rather than rubber. The weight will make acceleration more difficult, but it does not affect top speed at all. If you really want acceleration on a bike, you build one to take mountain bike wheels, but replace the fat mountain bike tires with 650mm road bike tires, like these.

The problem that most people have with these, andthat prevents more universal acceptance among the lycra clad elite, is thatthey are very quick to respond to steering, a little too quick for most. RoyJ isn't thinking properly with respect to Jeep tires either. People run bigger tires, and reduce the tire pressure to compensate, just like you would do on a bike. Bigger tires flex more in use, dissipate more energy, and require some additional horsepower to run. But the weight has nothing to do with it. Nothing.

Earle