tire pressure change to cure DW?

I recently switched off the 32x11.5s that came on my XJ for a more practical (in this city area) 30x9.5 setup - both tires BFG AT KO's.

Since i bought the XJ a month or so ago, I had not experienced the DW (btw, it has a 3" or so BB) with the 32s. But the day of putting the 30s on (with all four tires at about 32psi) I got big-time DW at about 45-50mph, at two seperate times on smooth parkway roads.

Obviously the change in tires had an effect. My question is - will lowering or raising tire pressures change/eliminate the problem? Which direction should I be going *assuming* all else is in good shape...up or down?

Is 32psi too high anyhow for regular street driving? (I don't offroad almost ever)

thanks.

im sure you did this, but to be the voice of reason i sometimes need, did you have the tires balanced? Any chance of taking it back and having them re-check the balancing?

By putting on a smaller tire I belive that you just pretty much hid the wobble. There still is a problem there its just not as noticeable.

I have 30x9.50 BFG at's. BFGoodrich said I should run them at 35psi on the street/highway pased on stock tire size, stock tire recommended pressure, and vehicle weight.

However I'm running them around 33psi now. Perhaps 35 was too much. I'm not sure if the centers wore out quicker because I didn't get an alignment after lifting for a few months....so it's hard to say.

33 will give better traction though. However, I never had any traction problems with 35psi.

StylerG said:

im sure you did this, but to be the voice of reason i sometimes need, did you have the tires balanced? Any chance of taking it back and having them re-check the balancing?

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I got them off a member who had them on his XJ (we swapped)....

As to balance, they feel very smooth at all speeds up to about 70mph (haven't gone faster), so if there's a balance problem it would have to be really small. But I will get them roadforce balanced when I get an alignment next week, just to be sure.

PornstaR said:

By putting on a smaller tire I belive that you just pretty much hid the wobble. There still is a problem there its just not as noticeable.

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huh?

I did NOT have DW at all with the 32s. Ever...

I do have it NOW (very occasionally) with the 30s.....

reading > you, lol

Blaine B. said:

I have 30x9.50 BFG at's. BFGoodrich said I should run them at 35psi on the street/highway pased on stock tire size, stock tire recommended pressure, and vehicle weight.

However I'm running them around 33psi now. Perhaps 35 was too much. I'm not sure if the centers wore out quicker because I didn't get an alignment after lifting for a few months....so it's hard to say.

33 will give better traction though. However, I never had any traction problems with 35psi.

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thanks, i'll play around with them, and do tread temperature readings (I race/autocross cars, so I'm pretty good at tire temperature readings, at least on my r-comps, lol)

Then you know how a properly setup suspension should work. Check for worn out stuff, it shouldn't DW. I autox too, Daily driver STS 91 civic Si.

markw said:

Then you know how a properly setup suspension should work. Check for worn out stuff, it shouldn't DW. I autox too, Daily driver STS 91 civic Si.

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lol, yeah....but combined with the unique drivetrain on an XJ (I am new to 4x4s completely) and the funky steering setup (never heard of a trac-bar before), and big tall tires, I have alot to learn about this kind of suspension, but it is obvious there is nothing "proper" about it!!

I was asking *assuming* the suspension itself is in good shape.

I tried STS and STX for a while, but the little cars like you were too numerous....

so I added alot of non-STS/X/U legal things and run my daily driver in E Prepared these days......they don't like chassis bracing in the ST and SP classes...




anyways.....I'm in a whole new ballpark with the XJ :roll:

um i had a shake or DW whatever on the front end. and it was because my tires were worn unevenly. i only had the shake at 45 mph or so a little over and little under. we rotated the tires and all was good. put the fronts in the back as they had high spots in the tread and drove on rough road to smooth them back out. i had this right after i bought the rig. the previous owner went too long without rotating the tires... so just to rule that out, run your hand around the tread of the tire and see if you can feel high and low spots. mine were really noticeable you could see them.

tclapp_88 said:

um i had a shake or DW whatever on the front end. and it was because my tires were worn unevenly. i only had the shake at 45 mph or so a little over and little under. we rotated the tires and all was good. put the fronts in the back as they had high spots in the tread and drove on rough road to smooth them back out. i had this right after i bought the rig. the previous owner went too long without rotating the tires... so just to rule that out, run your hand around the tread of the tire and see if you can feel high and low spots. mine were really noticeable you could see them.

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thanks, I'll give that a try.

Haven't gotten DW again since taking off the stupid 2" blocks on the rear.....