Tires wearing on outside

[vince1]

Well learned people I need some advice.

It's been a few years since I've got this old farm truck back on the road. Front end wise I changed it to power steering which means the pitman arm was changed and as I remember I also changed the lower ball joints (which didn't need to be changed). The link between pitman arm and idler arm seems to be running true so to speak with about 1/8" to 3/16" clearance to the cross member.

I recently noticed that the front tires are wearing more on the outside. Putting a square piece of plywood up to the wheels on flat pavement does not indicate that the wheels (camber?) are splayed out at the top. Top shim stacks are roughly 1/4" thick. Sighting down the wheels from the front to the back does indicate excessive tow in.

My question is, can too much toe in cause tires to wear more on the outside?

[SkinnyG]

Very often, the front track is wider than the rear track, so you can't always go by line-of-sight off the tires.

Rub your hand across the tread (inside to outside, for example). If the tread blocks feel "feathered", that is a sharp edge on the inside, and soft edge on the outside, that is toe wear. The sharp edge points in the direction of the "too much," be it toe in or toe out.

Not enough caster can wear the same way - the tires lose their "zero" camber and gain positive camber on a turn if you don't have enough caster.

[theastronaut]

Toe out wears the inside of the tires, toe in wears the outside.

Negative camber doesn't wear tires unless it's extreme, I run -4 front and -3.5 rear on my autocross/daily and tires last 20k+ miles driving it aggresively.

My other car has slight positive camber and will wear the outside edge a little faster than the rest of the tire, but it doesn't have any camber gain geometry built in, low caster, and has very soft suspension that allows a lot of body roll so the outside of the tire really tips over in corners.

[Gumby83]

I had a similar issue, i installed CPP lower control arms and their big disc brake with 2.5 inch drop spindles in the front on air bags. Did a string alignment and drove it for 75 miles. Outside of the tire wore super fast. i figured i must have too much positive camber and ended up pulling the shims on the upper. front and rear of the upper control arm had different sized shim packs. so i took the smaller of the two completely out. measured it with calipers and tried to get the exact same amount out of the larger shim pack then bolted it back up together. So far, it seems to have done the trick but i won't know yet since my camber changes with air pressure in the bags. heres a pic of the inside vs the outside wear.

[vince1]

I took out a .115" shim out of each of the four positions and lengthened both turn barrels 1/4 turn, then took it for a ride down the road and hands off it goes nice and straight. Sighting the wheels to the back they no longer have so much toe in. The differential was changed out to the wider 71 model some years ago but I don't know how much if any the width differs from the fronts.