blake

Interesting. Now here comes a newbie question:

Why do you guys run varying tire sizes?

The spec tires for the GT3 wheel are 235/295. What am I missing? Once this question is answered, I may be interested in your tires Doc2s!

Thanks,
-Blake

datax

Tires are just like your shoes or pants. Nike's size 7 might be equal to Adidas's size 8.5 or New Balance's size 6. So, MPSC's 295s are more or less Toyo RA1's 305s. Some run small while some run true on sizes. Well, that's one of the reasons. The rest are just because some want their cars to have more grip, oversteer, understeer etc, depending on how they set up their stuff.

blake

Okay. That makes complete sense. Now it's off to the archives to search!

Thanks,
-Blake

LVDell

Not suer just yet as the tires haven't seen the pavement yet. I'll have to talk to my race shop and get the pressures dialed in. IIRC the Pirelli HOT pressure was something like 30-32 yet this past month at Daytona Pirelli had changed that to something like 36-38. I'll know more after the next event where the tires want to be.

I know I know but that ain't gonna happen. I would have to part with my car and I'm not doing that

Crazy Canuck

So what size R888 should I go with? I'm running the 235/295 MPSCs.

255/315??

KOAN

I can offer a comparison of RA1s and MPSCs. MPSCs are very difficult to get up to temperature. Once they are there, they are significantly more gruppy that RA1s. However, the RA1s were good after the first lap, and lasted longer, both in the life of the tire, and in the stability of their grip. So, if you are spending 2-4 laps of a run group getting your tires up to temp, this is a significant consideration in time and money. I am going to try the R888s, as I've heard they are better.

blake

We are in the same boat Chris - I desperately want to hear this answer...

-Blake

On Pole

R6s are a little slower than the new BFG R1. I used to run my Pirelli Slicks at 26 psi cold.

multi21

Blake, I'd go with 245 on the front and 305 in the rear. As posted yesterday, I have 295 on right now, but I could easily go up one more size without a problem and get more rubber to the road for the rear

amfp

Pete, or others,

How do you find the 888's in rain?

Specifically if using as a street and track tire?

I read on Toyo site that are prone to hydroplanning. But that may be more to cover themsheves.

DanH

I run 235/295 factory sizes and had to have my arch liners in the front moulded and fastened back to prevent rubbing. Not much room in the rear for bigger either unless you are running huge camber and very stiff suspension. I'd stick with OEM sizes to be honest. They work just fine.

DanH

888s are very good in the wet with a bit of heat in them, but of course not good at clearing standing water.

mooty

stock suspension.
over 2.5 deg of camber
i run 255/315 R888, front only rubs at more than 1/2 full lock, rear has minor rub on fender lip.

DanH

I actually just had to replace my rears due to a radial gouge around the outer edge of the tread on one tyre. Happened when I went over a bump sideways (tyre may have rolled a bit?). Anyway just goes to show there isn't a lot of space there. I wouldn't be happy with rubbing you get as I drive mine on the road a fair bit.

mooty

i understand and that's why i made my post.
for ME 315 does rub, but the rubbing is very small will not hurt my tires. BUT IT DOES RUB PAINT OF THE "INSIDE" OF FENDER LIP. we are talking minimal paint here and you will not see it unless you remove the wheel and stick your head INSIDE the wheel well and look away from the longitudinal centerline of your car. if you roll the fenders lips, no rubbing. but i didn't roll it.

now there's no reason you need 315 for street driven GT3. on a track car... well there are other places paint get chipped off that's more severe than the fender rubbing so i am not too worry about it.

my post was not to negate or doubt your post. when i was deciding b/c 315 and 305's i was told the 315 will not rub. but it does, unless you have very stiff springs. like dell's or motons, then i dont thik you get rubbing (rubbing is from compression of springs when the car drops to a lower turn). most ppl will never see this rub mark. but i do detail the car to the n'th degree so i saw it