Hi,

Would appreciate any insight as to what's wrong with my car.

Recently because a puncture I changed my tires from stock sized P-Zero Corsa to GT2 sized (235/40R18 front and 315/30R18 rear) Toyo R888. Then I noticed the understeer on my car got a lot worse. (on my favorite twisting highway PSM kicks in around 10km/h earlier).

At first I thought it's the R888 being very new or needs more time to warm up, but now I have close to 1000km on them plus I've tried a few very long sessions, and the situation is not improving.

A friend suggested by widening my wheelbase, I am introducing more "flex" to the rear of the car causing understeering, and changing the swaybars would help (I'm still on stock).

Do you think that makes sense? Would appreciate any other input as to what you think might be causing my woes.

Thanks.

 

So there are a couple of things you should know about every tire manufacturere out there...

Get on tirerack.com and look up the tires you pulled off the car, and look up the tires you put on the car. Check the "specs" tab for the dimensions, width, sidewall height and do a little comparison of each... A Pzero of the same identical size may well have a very physically different overall dimension. You plussed up in size, which may impact this even more.

Also, the Toyo R888 isn't a real favorite among those who have bought and used it. The tire is heavy (lots of unsprung weight) and doesnt' have the overall grip of some others. You could disconnect your front sway bar (or set an adjustable unit to full soft) to dial out some of the understeer and see if that helps. You can also play with the tire pressure. Lower it a bit to see if you get more bite on the front tires... 2-3 pounds to start with and then add more pressure as desired.

The R888 is the last tire that I'd use on my 996TT, and is a tire that many have complained about. So much that TOYO is replacing it next year.

Mike

 

Mike,

Thanks for your comments. Guess I am stuck with the R888s since I just got them a month ago. Will try to get some H&R sways and play with the tire pressure a bit.

Ron

 

Mike
Do you have a R-comp recommendation over the R888?

 

I dont think going to the factory GT2 size tires is going to cause understeer and neither will the Toyo's. the car has natural understeer dialed into it so people wont kill themselves. The understeer can be completely removed but takes suspension work and sometimes alot of it. my car has no understeer and throttle oversteer whenever I want it.
I would consider a GT3 rear sway bar, lighter and cheaper than the H+R. The car on the street really doesnt need a front sway upgrade.
I would disagree with others as the comments on the Toyos, I have run several sets and had great success with them. again my car is not stock and I run 335 rear and 265 front so may be apples to oranges.

 

Tom, Your car is defenitely different from most. Although I agree that understeer is the norm for street alignments, those tires have a bad enough reputation that Toyo has ditched them for their spec series R compoind tire in 2010.

I can't think of an Rcomp that I'd run on the street. They are to limiting, to prone to punctures, and really a threat in the rain on public roads.

Mike

 

I heard they are bring back the RA1

 

so what's the best bet for a good street tire that can take 6 or 8 track events a year?

 

Mike,

I find it interesting what you say about the R888 or R compounds being a threat in the wet on the street. I had two good drives this year in the mountains and it rained hard on both, lots of standing water.

I drive with PSM off and found the RA's to be pretty darn good, I was tentative at the beginning but got really comfortable after a while, yes stay off the yellow lines etc and drive clean and smooth. Sure I had some sketchy moments over standing water but nothing I could not handle, made me a better driver for sure. I was running on 3/32 at that time too, with the fronts reversed on the last drive which really suprised me how well they worked.

 

Guys, I don't know everyone's driving experiences, and I'm hesitant to recommend an aggressive track oriented tire for street use.

Ben, You might well be a good solid driver who can handle the performance of the car. Some might not be... I've run in the rain on MPSCs with zero issues, but I've also seen guys destroy cars in the rain on Rcomps.

I'm enjoying the MP Sport Ribs as a great overall do it all tire, and I'm also liking the Kumho EcstaXS on the Miata as a street/train/track tire. Based on pics posted by another member after a couple trackdays on his SUmitomos, I'm not sure i'd be running them on the track.

If you're doing 6-8 DAYS per year, I'd say any of the top rated high performance tires will work for that, but if you're talking 6-8 events = 12-18 days, you should be considering a second set of wheels/tires for track duty.

Mike

 

Your quite right Mike, I appreciate you bringing that up. The RA's work for me but for most people doing street stuff and some track, MPS2's would be a good choice albeit pricey!

 

I don't think it's the R888's are that bad, I think the RA-1's were that good. World Challenge was faster on them as were all of the spec series of amatuer racing. I like the NT-01's for a street tire and track combo, though they are not rain friendly. The R888's may be the best in that regard as an all around tire.

 

some data from rennlist post...Toyo vs Hoosiers vs slicks
Speed world Challenge just posted their time for qualifying after not being at Laguna for a full season. Last time, they were on the RA1s.

Also, a very fast, consistant driver that has been running the Hoosiers, new slicks, and now the R888s, has posted times equal to his Hoosier times after learning the tires, and making chassis adjustements. We race Laguna Seca more than any other race group in the word and Kip Olsen, along with a few others have lap times as consistant and fast as any top pro team.
The results? Kip runs 1:29.low with slicks, has run 1:29.9 with Hoosiers and just posted a qual time with speed GT at 1:30.2. (even though most of the practices were in the 1:32s) I would say, these tires are every bit as good as hoosiers, maybe a tad slower (.25 sec. as I have seen) and after talking to him, and what I have experienced racing them, they require a different driving style.

He did put the tires on and was 1-1.5seconds slower until he made some chassis and driving adjustments. Now, it looks like the little NSX wit the big power and 225s up front, is doing just find against some top pro teams.

As for best overall street tire that does well at the track I stick with the Mich PS2's

 

Tom, That's one guy out of how many?

Everybody I know that was running R888s in 2008 in Private day rentals and DEs is no longer running them. Maybe they weren't willing to put in the time on these tires. The RA1s are gonna be back in rotation next year, so I'm not sure where that leaves the R888s, but I just don't know of anyone who'se kept on using them with that type of success... But hey, good for Kip!

Mike

 

I am on PZero's. I think the grip is great but after a while they flat spot and I get steering vibration which is a pain as I can't get rid off it with all the balancing on the world once there.

I am thinking going the Mich PS2's route. I have been told they are not as good in the grip area as PZeros but close.

Have you tried Pzeros, what is your uptake in tyre comparison?