tire sizes

[KillDevilBill]

Looks like im running 354 gears...what tire size should I be looking at for daily driver or best fuel economy? 31? 32 ?
I can tell ya im runnin 33/15's now and gas mileage sucks.

[chief1ton]

Well first off, the dif in a 31" to a 33" isn't going to make a big dif. It will also depend on what kind of driving you do most. Highway, in town. With 3.55s your mileage should be pretty good. i got around 14-17 ave, depending on how much i drove on freeway. My chief came with 3.55s. and 31"s so if you want to try a smaller tire i would say that's where you should start.

But if your mileage is really that terrible you should pro be looking into what else could be dragging it down. Tune up, bad carb, vacuum leaks, timing, ect.

[Ryan]

I ran 32's with 3.73's and they were a perfect mix of highway cruising and off-road capability. For 3.54's, I'd stick with 30-31's.

[Stuka]

I ran 30's, 31's, 33's, and finally 34's on my old Cherokee with 3.54's. 31's were the best for around town. 33's were better for HWY, but certainly hurt power. 34's really hurt performance.

As you go up in tire size, the difference is not linear. So going for a 30-31 is not the same difference as going from a 32 to a 33. The 32 to 33 will have a larger change to it.

Anyway, I would say stick with 31's.

[KillDevilBill]

I ran 30's, 31's, 33's, and finally 34's on my old Cherokee with 3.54's. 31's were the best for around town. 33's were better for HWY, but certainly hurt power. 34's really hurt performance.

As you go up in tire size, the difference is not linear. So going for a 30-31 is not the same difference as going from a 32 to a 33. The 32 to 33 will have a larger change to it.

Anyway, I would say stick with 31's.

Right on,,,, i'm runnin 33's now but I'm toyin with the notion of going down in size (lets keep this between us guys ) to maybe get some better gas mileage.
Sounds like the consensus is that from 33 to 31 wont make that much difference?

[KillDevilBill]

Well first off, the dif in a 31" to a 33" isn't going to make a big dif. It will also depend on what kind of driving you do most. Highway, in town. With 3.55s your mileage should be pretty good. i got around 14-17 ave, depending on how much i drove on freeway. My chief came with 3.55s. and 31"s so if you want to try a smaller tire i would say that's where you should start.

But if your mileage is really that terrible you should pro be looking into what else could be dragging it down. Tune up, bad carb, vacuum leaks, timing, ect.

Yep.. im on all that right now..

[KillDevilBill]

actually im around 9 or 10 mpg... dag gurn it

[Ryan]

33 down to 31 will make a sizable difference in the 'power feel' of your truck. It will feel like it accelerates faster off the line, etc. You will also get some mileage increase as well. Are you also changing wheels? I ask as to really gain mileage in stepping down tire size, you also need to change the width down as well. Something like a 31x10.5 would make a huge difference compared to the current 33x15.

[jeeping1974]

Even just going to a 33x10.5r15 would be better. You'll have less rolling resistance but still be able to keep the height.

I assume that when you say 33x15 you are talking about a tire that is 15" wide.

[KillDevilBill]

negative,, its 33/12.5/15's with 15/11wide rims. I realize that I will have to go with a 10 wide rim to go down from 12.5 wide tires.

[Ryan]

the 12.5's aren't terrible, but they do take a little away from mileage. The skinnier the tire, the less wind resistance they have (note that we are discussing skinnier tires for better wind resistance on a truck that is as aerodynamic as a brick)

[jeeping1974]

Ryan, it depends on how you hold the brick.

[Stuka]

negative,, its 33/12.5/15's with 15/11wide rims. I realize that I will have to go with a 10 wide rim to go down from 12.5 wide tires.

You run an 11" wide wheel with 12.50's? That is way wider than the recommended rim width. If you go down to 10.50's, you should have an 8" wide wheel. I even run an 8" wide on my 12.50's typically. 10" wide max. 9" is just about right.