Anyone care to diagnose my tire wear?

[Christien]

Below are pics of my track tires, in order, rear left and right, front left and right. They're Toyo RA1s, 205/50 ZR15 fronts and 225/50 ZR15 rears, mounted on 7x15 front and 8x15 rear fuchs. They've got about 8 or 9 days on them, 4 or 5 days at Mosport (high speeds, full size track) and 3 days at smaller tracks (lower speeds, tighter turns), one of which was in the rain. Only street driving is to and from the track (less than 1000kms total). Hot pressures were 36/34 F/R, but then lowered to 32/29 F/R. Can't say I really noticed too much difference, but then I'm having some other performance issues with the car, so I'm a bit more focused on that at the track. No sway bars, so lots of body roll, if that makes a difference. New (as of last year) Bilstein sport shocks front and rear. Stock 2.4L engine with Zenith carbs.

Any insight is appreciated!

Rear left:


Rear right:


Front left:


Front right:


Thanks,
Chris

[Zeke]

Yeah, run 'em some more! They look almost new.

[rallyracer]

in general, you have more outside wear than inside, so you can increase negative camber, or if you like the way the car is now, then flip the tires to even the wear.
David

[Quicksilver]

Generally you will run a higher pressure on the rear tires then you run on the front. The rear is doing more of the work.

Keep a notebook and worry about hot pressures at first. After you have a history of how the pressures change you can learn to estimate how much lower your pressures should be (depending on the current tire temp) when you start a run.

Important Note!
Play with the pressures on one end of the car at a time. If you raise or lower the pressures on both ends you don't learn a whole bunch. You work on one end to try and get the most out of it and then once you have an idea where it needs to be you play with the other end to try and optimize it. Once you have that it is a simple case of setting the end of the car with the least grip to its optimum setting and then dialing the other end's pressures to a point where the car acts the way you want it to.

When you're making entries into your notebook or studying the notes trying to find a good starting point remember that all tires are different. Race tires and DOT race tires generally require a lot lower pressures compared to high performance street tires.

Oh and a handy little tip when you are trying to estimate how warm a tire is when setting pressures after a break in runs: Don't feel the part of the tire or wheel that is in the sun. Feel the sidewall that is in the shade. Also check the rim where it is shady too. The rim can transfer quite a bit of the brake's heat to the air in the tires while it is sitting.

After keeping good notes from a few events you should be able to know what your desired hot pressures should be and what pressure to start with when dead cold or after a half hour or hour break.

[DanielDudley]

Not a tire expert, but I would say those look pretty good for tires that have had the cr@p kicked out of them. LR looks like it has a distorted casing. Once tires wear past a certain point ordinary analysis doesn't always apply. I think we are all assuming that the left side of the left tires is outside and the right side is outside on the rights. Any lock ups-spinouts ?

I would bet your street tires wear pretty good. I had an aggressive track alignment on my old bmw. Street tires always wore out the insides first. They had a full life though.

[tonythetarga]

I just looked at my RA1's. The center groove patern is deceiving, it makes you think that is the rotation of the tire, when in fact you want to look at the arced 'rain groove' lines of the outside sections. The wear shown on the left of the tires is actually inside wear, not outside. Pretty normal wear patterns for some negative camber. Keep in mind that most clockwise circuits are going to be harder on the left side tire wear (and bearings for that matter), especially the left rear, which is exactly what I see.
Christien, you need to go harder/faster through turn 2 at Mosport to even that wear pattern out

ps, you NEED sway bars. That will fix a lot of your handling issues.

[Rory Mckenna]

I agree.. after 8-9 days of track use.. I say they look rather good.

[bkreigsr]

that's not casing distortion the LR, those are flat spots.
a basic set of sway bars would go a long way to cure some of that.
IMHO
Bill K

[Christien]

Hey all, thanks for the info. I was a bit concerned about the wear on the left rear, despite the fact that all the tracks I drive are clockwise. I'm still a fairly novice track driver (3rd year of doing it) so I'm not driving the absolute piss out of them (yet!).

Wayne, yep, next step is to get a log book. The one problem I'm having is instructors always want to debrief when you get off track, and often have to get to another student, so I can't exactly tell them to hang on while I check pressures.

Daniel, what do you mean by a distorted casing? I've had a couple lockups, though mostly in the wet. I think I've locked up maybe 2 or 3 times, under hard braking coming into a very tight turn. (no brake booster, but factory upgrade (S-option) aluminum front calipers) No spins, at least not on these tires. Yes, my street tires are wearing very well, evenly and slowly - they're Pirelli P6000s which I've had on there for 3 years now, probably 15-20K kms and 5-10 track days (my first year and a half, rather slow) and very little wear.

Tony, thanks for the info about the grooves. I know I need swaybars, but they're #2 or #3 down the to-do list right now - a few other things are needed fixing/replacing first. They'll have to be welded from scratch, so it's not a cheap upgrade, unfortunately.

Thanks again for the help, everyone!

Chris

[tonythetarga]

FS: Early Front Sway Bar

front sway bar from a fellow Canuck in Alberta. No affiliation, just noticed. The early front bars were through the body, so no welding, but you will have to drill out the hole for the bar to fit through. Collect your bits and install when you're ready.