SC Rear tire wear

[BernieP]

I have a 1980 SC coupe and I noticed my rear tires are wearing on the outsides but the center portion still has good tread depth. I use the factory recomended air press. and check it often. The fronts are wearing evenly. The car has 6" and 7" phone dials with 195-65 15 fronts and 215-60 15 rears. This is my first 911, is this the normal wear pattern? Car is only street driven and was aligned when the tires were installed. Could a bad alignment setting cause this? Both rears are wearing the same way. Thanks to all & have a great week end!

[chuckr]

It is hard to tell for sure, but from what you have posted... I'd say it is the alignment.Porsches are hard to align properly.Get a good Porsche shop to align your car. It will handle better !

[stlrj]

Usually wear on the outsides means underinflation. You might need a new tire pressure gage.

Joe

[nostatic]

or too much positive camber?

edit- sorry, didn't see the plural ("edges"). nevermind...

[masraum]

I think from the description that it is wearing on the outside and inside of the tread, but not in the middle. Is that correct? Usually that's underinflation, but seems weird if you are watching your inflation. It might be worth it to check the alignment.

[BernieP]

Yes, both rears are wearing on both outside edges. I will confirm preasures with a second guage but I don't think that is it, that would be too simple. Thanks.

[nostatic]

just to clarify, each tire is wearing on both edges (inside and outside, 4 total wear edges), or each tire is wearing on the outer edge (2 total wear edges)?

If it is the latter I'll reinstate my camber guess.

[autobonrun]

Inside tire wear is something I live with. Because of its low height, I have run out of adjustment on the rear.

Still, the right person to do the alignment is key. I found my camber eccentric adjustment bolt was missing and the previous alignment tech did not notice. No wonder he couldn't dial it in. I added it when I replaced my rear torsion bars.

Make sure all adjustment bolts are in place on yours and are tight. Then have a reputable shop do the alignment. Also, check that all your bushings are still good and haven't flattened out on one side.

[nestorjw]

stop cornering so fast

[BernieP]

4 wear edges, the inside and outside of both rears, the center stil has plenty of tread left. Aprox. 23,000 miles on them.
Thanks

[Zeke]

Bernie, what pressures are you running? On my '77 S, I ran 4 more lbs. than in front. I would suggest at least that to get some more miles out of the present rears. I think I used 28/32 cold. You might go even to 36.

[beepbeep]

They are probably underinflated, you should try to run higher pressure. Factory pressure #'s were issued two decades ago for existing tires and tire-technology has moved forward a lot since then.

[Joe Bob]

23,000 miles? Geez, my rear tires are toast by then.....