toyo track tire pressures

[fredmeister]

I just mounted a set of Toyo Proxes RA-1 Competition tires for my 79 911SC that I use for DE events. I have front 205/55R16 and 225/50R16 rear sets that are unshaved tread and non heat cycled. I used them for the first time at Putnam Park 2 weeks ago and they felt like they were wobbling or squirming around alot in high g corners. I am not sure what my problem was, but am hoping for advice on 2 things.
1) what cold pressures should I run as a starting point to get the proper hot temps thru the tires? I was running cold pressures of 34psi front 38psi rear based on my experience with BFGoodwrich Comp T/A R1 track tires I had last season.

2) what negative camber should I be running with these tires? I am at negative 1 degree front and negative 2 degree rear presently.

The car is lowered and uses Welstmeister front and rear sway bars that were dialed in pretty well to get a neutral set-up based upon experience with street tires and the Comp T/A track tires used the last 2 seasons.

[avi8torny]

I just returned from Lime Rock....ran 32 psi front and 34 psi rear with the same tires. It was a 50 degree day and after many hot laps the pressures went up to 37 front and 40 in the rear. The car felt solid with no "wobbling or squirming". They stuck like snot.

[APKhaos]

Two points.
- The RA-1s can feel a little greasy before they have had a few heat cycles. They get much better with use.
- They build up temperature a lot more than street tires. You did not say what kind of ambient and track temps you had at your first event, but with ambients in the high sixties and a coolish track at VIR this past weekend, I was running cold pressures around 30F 32R to get hot pressures at 37F and 40R.

You really need to watch the hot pressures carefully - I've seen 'em shoot from 30 psi cold to over 48 psi hot - which is waaay too hot. They get very squirrely above 40psi, and it's easy to build up to silly pressures as the day/the track/your driving heats up. Check'em hot after every run, and come in if they are feeling loose - they are probably over pressure.

All that said, they are a great tire. I'm with TD - they stick like snot, AND they last a long time. Hoosiers are [much] better, but more spendy up front and much shorter useful life [heat cycles kill 'em quickly]

[hobieboy]

You should check out www.toyoracing.com
They have some suggestion about tire temperature & setup info on the tires. I believe I started with something like 28-30psi cold pressure.

[MMARSH]

No personal experience with the Toyos, But I've also heard that the wobbling or squirming around is pretty common if you run them unshaved. I was told they will get better as the tread wears down. If they are shaved, I was told they work pretty well from the start.

[hobieboy]

From my experience - they are great rain tires when new. To get good dry track, you have to pretty much wear them down (or shaved) till you can "barely" see the 4 grooves...

[nestorjw]

How long do those RA-1's tend to last with minimal track driving. I just had them put on my SC. I will be doing some track but more street. Any ballpark ideas?

[hobieboy]

I had them on my 930 last summer. Did ~12 DE days + driving back & forth the track. I think they can still last me another 12 DE days at this point (+ the travel).

YMMV...

[addictionMS]

I am running in the Toyo 911 cup here in the west, and there is a general agreement that a good starting point is 29psi cold all round.

http://www.911cup.com/

and yes they get much better after they are down to apoint where only the four grooves are visible to be really great. I started with a full treasd set last year and drove them an un believable number of times and they are now only getting good. My next set I will get shaved. In the unshaved state there is a set that takes place at the begining of every turn, where the tread blocks provde a "wiggle" first, once you get used to it, they are predictable.

a side note, Speeds Gt racers are now on Toyo RA1s, and they showed the tires pre race on the show and they too only have the four grooves visible.


Jim

[APKhaos]

The Canadian Toyo race site suggests that the shaved tires have a greater service life than the fully treaded tire. I can understand how the shaved tire performs better, but how does shaving help improve useable life??

C'mon you tire gurus - help us understand this one!