Spiffyjiff

after my last event at summit point, i noticed tire wear (quite noticeably) more on inner half of right rear tire than on outer half. why? my thought is: because my suspension is stiff, because i dont have LSD, and because the track is predominantly right handers, the right rear DRIVE tire is doing it's work mostly when right side suspension is uncompressed. i.e. around that particular track, the load will be mostly on the left side, so the right side suspension will many times remain more "cambered" (or however you say it = inner parts of tires more in contact with pavement than outer parts.) therefore, the drive tire inner could get worn faster than outer since it's actively spinning/slipping, etc.

does this make sense to ANYONE but me? any other ideas?

note that i have toyo 888's and the other 3 look "fine", bilstein damp's/rear toe links and cambered track alignment (all of which from pro indy shop), and it was driven at the event by a pro racer who said it felt great/needed nothing. in addition, i did not notice this wear pattern after VIR which is more balanced in terms of right/left turns.

George from MD

It's negative camber- I'm not sure what the stock suspension settings are but you might want to have the alignment checked. I'm sure Porsche has some negative camber on both front and rear as a normal setting. If you regularly track your car you might want to consider adding more negative camber (in front esp.) as the car will "turn in" quicker. This will increase the car's tendancy to tramline (want to dart right or left) when going straight and you'll go through tires quicker but it's all part of the slippery slope- on track performance v. street.

Charlie Murphy at Intersport or Mike Levitas at TPC are two of the masters in the DC area and can set it up correctly for you.

Edgy01

The higher negative camber is dialed in by the factory to enhance your handling capabilities. If you're wearing the inside too much (relative to the other areas of the tire) then you are not driving aggressive enough. It's doubtful to me that you are experiencing any slipping at all with the right tire. If you stick to a track you may need to develop your own suspension alignment settings for that particular track. Recall, the factory settings are an idealized setting, based upon what they anticipate drivers will need for optimal handling on a variety of roads.

cparkin

Have you called Tom yet? I would start there.

Spiffyjiff

yep, he's the one who suggested a (non)LSD issue may be contributing factor. i simply expanded my thought process on that, knowing that some racers prefer to have their camber dialed in for a particular track - meaning, for a right hander track, more camber on left than on right, etc. thus, because i have the same aggressive camber on each side, the (primarily) unweighted side could experience faster inner tire wear.

in any event, i plan to do a pre-season alignment with them next year.

aj986s

IMHO, I think what your experiencing is wear due to wheelspin on the unloaded side, due to not having a LSD. This happens a lot in T6 at Summit Point because it is a long sweeper. As you're trying to apply power, the unloaded tire on the right can easily begin spinning, and my guess is the wear you're seeing is due to this. I think its highly unlikely that the unloaded tire is wearing so much simply because of camber. In fact, with a properly setup car, you should be seeing more wear on the left side tires because, as you mention, Summit Point is mostly right handers. The left side tires are doing alot more work during cornering forces. I suspect, your stiffer suspension may be holding the car relatively flat, and the onloaded inside tire is maintaining some negative camber attitude going into T6, and consequently wears the inner half of the tire when it starts spinning.

FWIW, because of these sorts of tire wear conditions & issues is why I like using symetrical track tires so that I can rotate & flip as needed to get max mileage out of them.

Spiffyjiff

hey tony, it's chris m. in case you dont recognize me. thanks for the info, that's what i think too - drive wheel spin, esp in T6. (something silly is also happening on exit from T2 but unsure if it's car or driver error!) and hey, this never used to happen in autocross!

see you next season.

racer

You left out the part about skill level, so I assume you drive "flat out" like everyone else!

While I think the non lsd "slip" is part of the reason, It could also be that, if the car is in fact "drifting" or near an edge of adhesion, you could be wearing the tire from both "forward" and "side" angles.

I have several pic of my old 911 track car, and can see the "inside" rear wheel is sitting on mostly the "inner" 2-3 inches of rubber (the outside edge sticking up off the fround by 1" or so )and was in fact, being "dragged" sideways through corners.

One other potentail contribution could be tire slip on the rim. On the same 911, at SP, I marked a spot of rim/tire on all 4 wheels. I then ran a session or two, and later noticed that 1 wheel didn't "slip" at all (ie, the marks were still even from rim to tire) to another wheel that had "slipped" as much as 5" on the rim.

mdrums

We can't really tell you anything with out knowing what the real camber and especially toe is set at. What are your alignment specs? I will tell you that toe will wear a tire faster than camber.