At the race track today the Toyo rep convinced my to get a set of RA1's. We had a long discussion about the S2000, race tires, other brands, and sizes, I looked at a set that were the correct rear size (245/45ZR16) and front size (205/55/ZR16) sitting outside the Toyo trailer. I said, "I'll take those."

While the tires were mounted and balanced, I got into a discussion with a BMW guy about tires, brakes, and track time, while keeping an eye on the tire mounting progress. Needless to say I must have blinked, and he mounted 225/50ZR16 rear tires. Of course I didn't check this at the track, and didn't notice the mistake until I got home.

So I did some crude hand measurements and spec comparisons and it appears to me that the "wrong" 225 size tires are closer to the OEM S02's than the supposedly more correct 245 size. In particular it looks to me like the tread width on the 225 Toyo tires is about 8.5 inches, which is the same as the stock S02's.

Am I missing something here? In general, do you think I will be happier on the track if I insisted on tradiing out the 225 tires with the Toyo 245/45ZR16's?

 

I would suggest checking the size of the contact patch, you my find that the Toyo's are close to the S02's where-as most tires compared to the oem S02's are not.

Anyone can correct me but I thats what I would suggest.

 

Gloffer, Can you check the tread width of your Toyo fronts and compare to the SO2's. Seems like some 205/55/16 tires are wider than our SO2's fronts and the rears needs to be wider to keep the balance. I wish all the manufacturers would list their tread width and contact patch. I guess the rim widths would make some difference, but at least it would give us a general idea. Bridgestone seems to be one of the few that gives a lot of info.

 

I measured both brands of tires at the same points across the tread using a tape measure on fully inflated tires. The Toyo front size (205/55/ZR16) has a tread width of about 7.5 inches. The Bridgestones (205/55/ZR16) have a tread width of about 7.0 inches. Note that the Toyos are mounted on the car and the Bridgestones are dismounted. This might affect overall width, but should NOT affect my hand measurement of tread width.

This measured Bridgestone tread width compares favorable with the TireRack spec of 7.1 inches. The spec sheet for the Toyos does not have tread width as one of the measured parameters. The closest I could find is overall width which for the Toyos fronts is 8.3 inches, this measurement for the Bridgestone fronts is 8.1 inches.

The rear measurements for the Bridgestones (225/50/ZR16) are: tread width from the spec sheet and by hand measurement 8.5 inches, the overall width is 9.2 inches.
The rear tire measurements for the Toyo (225/50/ZR16) are: tread width hand measurement 8.5 inches, the overall width is 9.0 inches.
The rear tire measurements for the Toyo (245/45/ZR16) are: tread width hand measurement 9.0 inches, the overall width is 9.8 inches.

The other measurement of interest is the Overall diameter and from the spec sheets the numbers are:
Bridgestone front: 25"
Toyo front: 24.7"
Bridgestone rear: 24.8"
Toyo 225's: 24.7"
Toyo 245's: 24.4"

So, based on these measurements, whaddya think, should I insist on trading out the Toyo 225/50/ZR16 and get the Toyo 245/45/ZR16 rear tires or are the rear Toyo 225/50/ZR16 a good match for the stagger needed by using the Toyo front size 205/55/ZR16?

 

[QUOTE]Originally posted by Gloffer
[B]I measured both brands of tires at the same points across the tread using a tape measure on fully inflated tires. The Toyo front size (205/55/ZR16) has a tread width of about 7.5 inches. The Bridgestones (205/55/ZR16) have a tread width of about 7.0 inches. Note that the Toyos are mounted on the car and the Bridgestones are dismounted. This might affect overall width, but should NOT affect my hand measurement of tread width.

 

Just to close the loop on this.

I went back to the Toyo Rep (who happens to work out of a local BMW dealership) and changed out the rears to 245/45ZR16 size. I guess the "mistake" turned out relatively fortuitous because the the larger size tires are an extra $10 per tire and although they wanted the extra $$, I cried and ended up NOT paying any extra. Of course this is negated by the extra hassle and 2 hours it took to get the changeout done. So the whole deal with mounting and balancing turned out to be $729. I think that's a pretty good deal for a set of Toyo RA1s (in the correct sizes no less).

I broke in the tires by driving hard the 25 miles from the dealer back home. And now they're off the car waiting for my next track day. By the way, the hand measured tread width on the Toyo RA1 245/45ZR16 is 9.0 inches, vs. the stock S02 rear thread width of 8.5 inches. This should maintain the correct stagger since the Toyo 205/55/ZR16's on the front are 1/2 inch wider than the stock S02s too. I edited the data post above to capture this.

Although I drove home top-down, those Toyos seem just as quiet as the S02's and they sure do seem to stick. The Toyo rep said that some guys are driving over 60 miles to track events and then driving home on these tires. Might I consider these for use on the street??

The Toyo rep recommended 32 psi front and 30 psi rear cold pressure on unshaved tires. This is kinda freaky to me because I've been running higher pressures (35 psi cold) on the S02s at the track. The rep indicated that the RA1 sidewalls are stiffer and higher pressures aren't needed. Of course this will iron itself out at the track by comparing actual tread wear to the tread-use indicators, but I was wondering if ya'll thought this was a good starting point for tire pressure.

Thanks for the advice.

 

Ive used my RA1s on my old BSP GSR on the street with great success. Mind you because they were all the same size I could rotate them constantly, but there is nothing like destroying everyone on the road in the corners all day long. I think it would be sick in the S.

I began using them only for events, but eventually I had way too much fun driving back and forth to take them off between.

Im seriously considering driving RA1s all summer long on my S. The only problem would come if you get rained on heavily.

 

I ran Toyo RA-1s as track and street tires all summer. About 8000 miles, 8 track days. I really liked them in both uses. I have 17" wheels, so sizes and sidewall are different. Some track folks have said that the RA-1 has a soft sidewall, but that's in comparison to Hoosiers and Kuhmos.

After all those miles and track use, the tread is pretty much gone, so I can't use them if it looks like rain, but they're still very good on the track. They don't seem to have been hurt by excessive heat cycling.

I usually run about 33-34 psi rear and 34-35 psi front, cold for the street, and at the track keep pressures in the high 30s, hot.

Ted