It’s been probably 10-15k since I rotated them. But this pattern shows up on the front and rear tires. Tires still have wheel weights on them. Lugs that are black probably have 1-2 32nds of wear more than the others.
I’ve been running them at 35psi on the street, but the tires are rated for 80psi.
When you are running too much pressure, you usually get center wear, the center of the tires bulge out more basically and wear faster. When you have too little pressure, the center of the tire doesn't have enough pressure on it, and the outside edges wear more (as I understand it) and so you can figure out if your pressure should be higher or lower based on how they are wearing. With too heavy of a tire (in terms of rating and psi) your ride may be still too rigid at that pressure though, (for example an E rated tire on a vehicle that would use a C rated tire).
I suspect in your case you are running a bit too little pressure, and the cupping may have to do with worn shocks. you might have just a pinch too much toe in as well from when the were on the front. I've had cupping on every set of geolanders I've had, so I'm not really the best for figuring that out.
The cupping on those tires in my opinion is excessive toe. Inducing excessive toe on this forum as a good thing is widely advised and I don’t subscribe to it.
I set my caster to factory specs which is 2-4* and adjust toe as close as I can to factory specs which is 0.
Make sure your axle and tie rod ends are in good shape and your good to go.
Thats what I've been running, my truck seems a bit touchy, like it wants to dart to the right or left a bit easy, because these are AWD and the driving force is being applied to the front tires ( a force wanting to pull the front of the tires inwards), I believe they may operate better with less toe in, as compared to similar vehicles with RWD.
In a RWD vehicle the car will push itself forward from the rear, the resistance of rotating the front tires will want to pull them back slightly (outwards from front end of tire), any slack in wheel bearings (which you are supposed to have), trunion bearings etc can pull the tires back or outwards, which would be corrected/engineered with slightly more toe in.. Just my opinion, probably the majority would agree though I think.
Toyotas spec for toe is 0, no toe, non at all. All I see on here is people with light steering feel being told to add toe.
I tape measure my toe and error on the safe side and do have very little toe.
I've been going with a bit of toe in, but I think close to zero toe in I will try next. However mine is less than close to stock so not really a fair comparison.
in the 92 manual:
In the 96 manual: