BP5 legacy tyres front inner shoulder wear

[BP5Nut]

Hi all,

So my car failed a warrant the other day due both front tyres worn on inner shoulder. All tyres were replaced approx 35000km ago, (RE050A's), with an alignment done at the same time. I'm a tad frustrated as the front tyres - apart from the inner shoulder, have about 4mm of tread left, same as the rears, so was hoping to get another several thousand k's out of them. The wear is right on the edge, only the edge block is affected, and even then only really the outer half.

The last time the tyres were replaced was for the same reason. I was kinda hoping/expecting the alignment done after replacing them would have fixed the inner shoulder wear issue, but obviously it didn't. I'm pretty careful with tyre pressures, usually check at the petrol station before any long trip.

Car is a BP5A GT Spec B (18 inch stock rims, 215/45R18).

Is anyone else experiencing this/have any advice for preventing it occurring again?

As a side note, I'm also considering changing to a 225/40R18 size for a bit more choice in tyres (looking at Michelin PS3's) - good/bad idea?

Last alignment report if it's any help:

[gotasuby]

you dont have enough toe in on the fronts. subarus toe out while driving. hence shoulder wear. factory specs are ****

[Andy_Mac]

Without trying to threadjack what kind of rough numbers would you be looking for wih other areas? Never really know what to tell techs so just let them do what they want. Getting mine done this saturday withh the new tyres, just a bit more camber, front and rear, to fit wider wheels in there rhan normal

[GC8E2DD]

We went 225/40/18 at the last change - no regrets there. You did well to get 35,000kms out of RE050As. We went through two sets in under 50,000kms before giving up on them. We tryed some Kumhos in factory size after that which were every bit as good for road driving, and now have Zetums in the size you mentioned which is a tyre I've raced on for the last two years (on a different car).

Your alignment looks fine, although it used to have a lot of toe. I wonder what it looks like now. I ran 32-34 all around with the Bridgestones as the mood took me and they wore pretty evenly. I wouldn't entirely trust service station gauges though; worth getting your own.

[gotasuby]

I run 1.7 degrees camber front/1.2 rear. 3mm toe in rear and 2mm front. Get dead even wear. On lowered car

[lachlan]

inner shoulder wear is lack of front castor . as a lot of 4wd cars have .

[GC8E2DD]

That doesn't make sense. As you turn into a corner and the outside front compresses, it rolls into positive camber which is outer shoulder wear. More caster introduces more negative camber in the turn to the outside wheel. Is the inner shoulder wear from lack of caster supposed to be on the unloaded wheel?

[BP5Nut]

Thanks for the info guys, think I'll get a bit more toe in put on when I get my tyres replaced in the next few days or so. The specs allow for up to 3mm F&R so will probably go pretty close to that.

Hadn't thought caster would affect it much, but after asking google it seems like it at least probably isn't helping. The specs for the Spec B are 6.05 deg, which is somewhat different from the 5.31/5.28 measured (and not changed) in the last alignment. Anyone know if it is possible to adjust the caster on these cars?

[loner]

It's not possible to change the caster... and too much toe will destroy tyres faster than anything else.

[gotasuby]

its hard to change caster, but possible. you need different top hats.

Static toe is good as subarus toe out when driving along. all my specs do is make it near neutral when driving.

If i had mint bushes i could prob push 1.5-2mm

[GC8E2DD]

You get about half a degree from the Whiteline ALK from memory. I think I got about a degree from top hats on factory struts. I think the Leggy LCAs are two piece like the Imprezas so you could possibly do the 'free caster mod', and maybe even use spacers. I still don't get how low caster wears inner shoulders though =\

[DRFVDR]

So in 35,000 km you never rotated your tires ?

most manufactures require rotating every 10,000 km

will wear the whole set evenly, which is perfect

[gotasuby]

 GC8E2DD said:

You get about half a degree from the Whiteline ALK from memory. I think I got about a degree from top hats on factory struts. I think the Leggy LCAs are two piece like the Imprezas so you could possibly do the 'free caster mod', and maybe even use spacers. I still don't get how low caster wears inner shoulders though =\

Low caster doesn't affect inner wear.