Outer Limits 4x4 Board

I've got some strange wear on my tyres, 2000 Patrol coil cab 50mm body lift 50mm king springs koni shocks 37 inch Michelins. The tyres are wearing in round patches { about 75mm round } staggered evenly { about every 400mm } around the tyres. Some people call it scalloping others cupping. I also drove on some wranglers for a few months and they started to wear the same way. so far i've eliminated every possible cause I can think of. I've been through the whole front end ie: swivel bearings, wheel bearings. i've had the problem for a while now and in that time i've replaced : springs shocks steering damper drag link tie rod { both superior engineering } all bushes { genuine nissan }. wheel alignments have always been trouble free, wheel balancing has always been hard with these michelins { bought second hand ex military } but the goodyears were balanced perfect { zero shimmy or vibration }. the car steers and handles great and the castor is good. I'm at the stage where i'm starting to think either a bent axle housing { though i'd think they'd pick that up when doing a wheel allignment], or a bent chassis, though there's no visual evidence of this eg: does not crab when driving and the few measurements i've done around the chassis look symetrical. I'm out of ideas, am I overlooking something?, any thoughts? oh yeah, it's only the front tyres.

what tyre pressures?

Well i've mixed it up a bit and tried evrything from 25 psi to 42 psi. The michelin tyres im running are truck tyres with a very high load rating. The sidewalls are quite stiff at road pressures and look acceptable for road use right down to 28 psi. I've settled on 35psi front and 32psi rear { tray no load ] . The wranglers I ran at 35 psi all round

pressure sounds good.do you know what your toe in is?. we had a rule of thumb of stting up nissans with 0mm toe, so basically the wheels are dead straight.

No don't know what toe in is set at, I always just leave it to the local bob jane bloke. I pretty much trust the bloke and he's the only boke who can do a reasonable job balancing up the big michelins. I'll have a chat with him, so zero degrees hey? is that the factory setting?

zero millimeters. some early nissan utes ran that spec, but with rubber like yours you might have to improvise.

Are your shocks OK?

yeah my shocks are good. that's the first thing everybody says in relation to this problem. for a while I thought th e shocks may have been having a hard time controlling the weight of the 37 inch michelins but the 35inch wranglers I ran for a while are a fair bit lighter and they had the same wear pattern. I'm running Koni heavy track shocks and for the money I would'nt use any thing else these days. I ran these same shocks on my rangie with 35's for ages and never had this sort of problem,

thanks for the info JoeBlow I'll get it chacked. now, do you think the toe in setup could cause this type of wear?. I thought it would just cause the inside or outside shoulder of the tread to wear evenly around the tyre, not in patches.

iside and outside can also be attrbuted to camber.

Poor quality/worn wheel bearings??

Sound more like a "resonance" pattern rather than an alignment issue. In fact having 0mm toe in may be the cause - try dialling in about 5 mm toe-in for a few thousand km to load up the bearings and bushes and see if the wear pattern straighens out.

Other possibility is some obscure resonance from the halfshafts, or a worn CV causing a slight "hammering" ESPECIALLY if you have 6 or 12 of these wear patches equidistant around your tyre.

Yeah DamKia that's an interesting one. I'll get an allignment when i get a chance and see what the toein is set at, failing that, it just so happens i've got a whole GU front axle assembly sitting in my shed so i may end up doing a swap and see if that works.
Do you think a bent front housing could cause that wear pattern? Just wondering if I should swap the whole assembly or just swap the innards ie: centre, halfshafts, CV's? I'd have to swap the guts over anyway because of locker and ratios.
I did the wheel bearings about a year ago when I did the ratio change {Timkin bearings} and adjusted about 3 months ago and this problem has been ongoing for longer than that. The thing is that the Michelins are a pretty hard compound and it took ages to wear this pattern into them, even at one stage I thought i'd fixed the problem after some new radius arm bushes and a tyre rotation but 6 months down the track I can see the pattern again.
I've got to get this sorted before I fork out 2 grand for new tyres.

What are the actual rim's themselves like? No buckles or flat spots?

rims are good, has done this with 2 sets of tyres and 2 sets of rims.

Is it only front or all four.

Do you rotate the tyres regularly.

Seems to me too that it's some resonance thing.

Sorry if I have missed something you already stated, but are we talking just the two front tyres or all four?

edit: lol I just saw Eddy asked the same question.

We did have some worn patches on a small truck where I used to work and as far as we could tell, it turned out to be some bad braking behaviour by one or two of the staff who drove it, basically you could make the thing skid a bit for fun, especially at the back with the tray empty.

No Chimpboy I don't have such bad braking habits. With these tyres and standard brakes I doubt if i could get them to lock up, ha!

I was just thinking today, the stub axle { spindle } that the wheel bearings run on, if this was bent or worn, may be the cause.

Anyone ever bent a spindle?

Was thinking that the wheel bearing may be hopping on the spindle, though I didn't notice any slack last time I had them out.

steel wrote:I always just leave it to the local bob jane bloke. I pretty much trust the bloke

its a fair bet thats your problem right there


my brother bent a stub axle on a falcoon. It had tyre wear and handling problems. hehad wheel alignments done by several diferent mobs and was told it was spot on everytime. eventually one guy picked up that the stub axle was bent. once it was fixed the alignment was fixed properly.

80's_delirious wrote:

steel wrote:I always just leave it to the local bob jane bloke. I pretty much trust the bloke

its a fair bet thats your problem right there

That was my first thought, too.

You have a difficult problem. Your Bob Jane bloke might be really nice bloke, and be trying hard, but at the end of the day his business is selling tyres - wheel alignment is a secondary function.

Your unusual problem requires a suspension specialist, not a tyre specialist. Hit the phone. Most shops will say "drop it in, we'll have a look" - you don't want that. Keep phoning until you find someone prepared to take the time to discuss your problem, listen to what you've already tried, ask you questions. Speak to enough shops and, sooner or later, you'll recognise the one you need.

Suspension '' specialists '' around here are no better, they're just parts installers.
last night me mate gave me the name of a truck allignment specialist.
It's a fair hike but i'll give him a go
Thanks guys, jason.