outer tread tyre wear, on left front wheel

[drexx]

02Nov2003 (UTC -7)

On my IFS'ed UZJ-100, the outer tread on the left-front tyre is wearing unevenly. Asides from bad shocks (waiting to be fixed with OME LTR's), is there any other opinions on why this may be happening? Do I need a front wheel alignment?

All other tyres are fine. Thanks in advance!

 

[IdahoDoug]

Describe the wear. Also, gently run your hands over the tire treads in the direction of travel, and back around. You're looking for "feathering" of the tread blocks in which one direction or the other your hand will tend to "catch" as you rub your hands along the tread. Compare it to the other front tire and see if you note a difference. S/b in the same direction, but if not you might also look for a frozen/corroded caliper on one side of the front.

But alignment would be a key step - sounds like something's loose or bent on the worn side allowing it to toe in. Yank on the tire very roughly in all directions and see if you can feel anything loose, inspect for bushing damage, and do the same with the tire off the ground.

Doug

 

[landtank]

Yup, sounds like time for a wheel alignment. If there is anything else in there they should spot it before doing the alignment. Unfortunately once a tire starts to wear irregularly it will wear that way til the end. So don't look for wear improvements after the alignment on that tire. Most shops provide a print out of factory specs, before and after readings on your vehicle. Take a little time to read the printout and it should make sense and show you where the problem was.

 

[cruiserdan]

Ditto.

I think maybe toe. Rick is spot on about the wear. If it is not too bad yet, it may come out of it somewhat if you move it to the opposite side rear and run it there for a while. X pattern rotations are acceptable with modern radial tires(unless they are directional, like mine :whoops: )


D-

 

[Rich]

I suspect that the camber is off on the left side. Wouldn't incorrect toe affect both front tires equally?

Rich

 

[landtank]

Rich,
Not always. When you drive the truck/car the rolling resistance of the tires will cause the suspection to flex back. So the once static setup with some toe in now has none, and the tires point straight ahead. Now this is all well and good in theory, however each side will flex differently and with increased/decreased toe they will have different effects on each side.

This is why with these larger tires higher inflation rates actually help the truck. On another thread someone mentioned increasing the toe for better responce. This will help overcome the increased rolling resistance of the larger tires.

 

[Koffer]

Heck I dont know, but maybe the pix in your sig line has something to do with it needing a wheel alignment ? :

 

[IdahoDoug]

Rich,

I agree with you on the camber thought. It would make more sense than simple toe in since if one side is pushing, it's pushing against.........the other front tire. Thus either the truck would be turning constantly, or the driver would turn the wheel until the other tire's slip angle matches the problem side so he could go straight. Good call. Still need a good description of the wear, also.

Rick,

Couple comments on your thought. The suspension shouldn't flex back from mere rolling resistance and change your suspension angles. That would indicate serious problems. In addition, the 100 being full time, the front tires are getting torque and would actually be pulling (which shouldn't change your suspension angles, either).

On the toe in suggestion for larger tires, this is a common setup sometimes used in competition to pre-flex the tires for crisper turn in, but for a road vehicle it will cause a lot of wear for this minor change in handling feel. Finally, higher inflation pressures won't change alignment - larger tires or not.

Doug

 

[landtank]

Doug you would be suprised what a little change in rolling resistance will do to an alignment. Back in the day :, steel belted tires were just coming out and we had to alter the alignment specs to compensate for their reduced rolling resistance if those tires were used. Especially with an IFS setup, it's not about a bad part but more of an accumulitive effect from many joints some mounted in rubber.

 

[IdahoDoug]

Uh oh, we're both about to date ourselves.

The radial vs bias ply alignment changes were an extremely subtle thing - much of it urban legend but also some truth to it. The truth part was that the older bias ply tires were not as directionally stable and often wandered one direction or the other due to a tire property called conicity and manufacturing variation. To fix it, alignment guys in "the day" would indeed add some toe in and trade off some wear for the stability of two tires gently pushing against each other. Radial tires brought new construction techniques as well as generally higher production quality and consistency that eliminated this need fairly quickly.

Regarding changes to actual suspension geometry from mere rolling resistance changes, I'll continue to disagree that's an issue. If that small a force (perhaps 7ft lbs of torque at the contact patch) could move suspension parts around, consider what max braking would do with perhaps 200 ft lbs of torque - you'd never stop in anything close to a straight line. In that scenario, things in the suspension would be wobbling all over the place - IFS or solid axle. They're much stouter than that.

Ironically, this is one of the things I'll want Drexx to check - tightness of suspension components, bushing condition etc but I guess we'll have to wait 'til he's back from jumping the truck over another sand dune to find out......

Having said all that, it's always amazed me how well long distance truck tires can wear, with some of them warranted over 100,000 miles I've heard. Sounds like you've had some experience in this realm. Incredible.

Doug

 

[drexx]

02Nov2003 (UTC -7)

Thanks gents, for the replies.

Here's what I found again:
1. I took a tyre depth gauge, and saw that the outer tread was 9/32", while the middle and inner tread was between 11/32" and 12/32". All other three tyres had 11/32" and 12/32" tread depth too (after 45,000+ miles! I wonder how long can I last with my 5-tyre rotations? 8) )
2. I have BF Goodrich 285/75R16's, at 35psi cold
3. I grab each wheel and shook it as hard as I could, with my 210lb frame not disturbing the 6,500lb 'Cruiser one bit... I didn't have chance to put it on jackstands though
4. The weirdest thing? I felt and really looked at the outer tread pattern... it was a sawtooth pattern?! WTF happened there? ??? I checked the rear-right wheel, where it once came from my left-front (as part of 5-tyre rotations), and it was noticeable, but not obvious. Apparently, it's been going on for some time but my wife didn't notice.

 

[landtank]

Drexx, dude you just need an alignment.You're jumping sand dunes, your wife's probably a curb jockey and the truck is just probably do. I'd put the 2 best tires on the front and then take it in.

One other thing you might check is the torsion bars. Put the truck on a flat level spot and measure from the ground verticle to where the torsion bar sits in the lower arm. They should be the same. If they are not then that should be adjusted prior to the alignment

Doug, my experience with front ends is basically some schooling and a 1 year stint at a Goodyear dealer, nothing to brag about. But I did see some unusual situations though. We had one customer that was tearing up his front right tires. On the rack several times and checked it out repeatably with out any luck. Finally somebody asked about his wife. Turned out see was a hefty woman . So much so that we had to align the vehicle with her sitting in it! Problem solved!

 

[IdahoDoug]

When you go in for the alignment, get the numbers for ALL FOUR wheels. I went through something like this with my bro in law's 80. The alignment guy will simply plug in the vehicle's year and make and because the 80's rear alignment cannot be adjusted, nor can some front angles it only checks certain angles when he pushes the button and lets the machine go through the moves. Put it on the work order that you want to see the alignment specs for all four wheels even though you cannot change some of them. It's nutty how they are. He had a bent rear spindle and I/we knew it full well. We needed the numbers, but paid for 2 alignments with guys telling him after "Oh, well that's not adjustable" even though he'd done what I asked (so, didn't provide the numbers). Finally, he put it in writing on the 3rd and got the numbers he needed.

So get all your numbers and if they protest 'cause they have to put the Hunter into manual mode to measure the rears then go down the street...

Doug