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Widest R-spec choices in 18's???

 
Old 01-15-2007, 07:23 AM
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333pg333
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Default Widest R-spec choices in 18's???

I've done a bit of a search on here and brand specific sites but I'm not getting all the info I want. What are the widest in 18's and what are your opinions of these? This is for 4-6 lap events on circuits.
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Old 01-15-2007, 01:04 PM
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Kerry
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For the Kumho V710 it's the 315/35 tire. It's an excellent autocross tire but most people don't use it for tracking as it's designed to get hot very quickly, so it can get too hot on the track after a half hour of continuous running. But maybe for a 4-6 lap event that's want you'd want?
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Old 01-15-2007, 04:14 PM
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Hi Kerry. Have you used them on the track? As you say for short sprint events these may be ideal. Thanks for your input.
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Old 01-25-2007, 05:57 AM
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Any 305's in R-spec 18" ?
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Old 01-25-2007, 08:08 PM
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DOT-R 18 inch tires

Michelin PSC: 345/30

Toyo RA-1: 335/30

Hoosier A/R6: 335/30

Yokohama Advan A048: 315/30

Kumho V710: 315/30

Pirelli PZero Corsa: 315/30

Goodyear Eagle RS: 305/30

Toyo R888: 295/30

BF Goodrich R1: 285/30

Buyer beware. The manufacturers published sizes that are not alway accurate. Some tires simply run wider than what is listed.

For very short events such as what you have described, an autocross tire may work for you such as the Hoosier A6. The rest of the tires were designed for road racing. The Goodyear RS and Hoosier R6 will give you better lap times, but last the shortest. The RS is being redone and will be available later in 07. The Kumho V710 comes closely behind these two and lasts a bit longer than the R6. Your experience may vary depending on the type of car you drive and its suspension setup. The Toyo RA-1 is very popular because it is an easy tire to drive and maintains a high level of performance for a very long period of time.
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Old 01-25-2007, 09:00 PM
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richard glickel.
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Well, of course this depends on what width wheels you're using and offsets. On 8.5 x 18 front and 10 x 18 rear, you can run 245's (front) and 285's or 295's in the rear. That was my set-up last year - no issues. With 9 x 18 (front) you can use 255's

With 9.5 x 18 front and 11 x 18 rear, you can use 275's up front and 315's in the rear (but you may have to roll the rear fenders). This is what I will be trying on track this season.

Good luck!
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Old 01-30-2007, 01:49 AM
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Thanks guys, good info. I have been using the R888's which are very good. 9x255's and 10x285's. I would like to go up to say 10x285 and 11x315's if poss. but I've not heard of anyone running these on a stock car ('89 951 which has factory rolled fenders) and as stated, they are often wider than is printed on the tyre. I am in Australia and I don't think we have the Goodyears R-spec or the Hoosiers at all. I was thinking if I can't fit the 315's to try 305's but these seem pretty rare? The Toyo's are great in that they get to heat very quickly (1 lap-ish) and they last for longer than the 5 laps or so that you hear on the Hoosiers. While the bulk of my trackdays are short 3-6 lap SuperSprints, I'd be concerned that the Hoosiers would wear out very quickly with what I imagine is a very soft compound.
The car is an '89 951 which is mostly stock weight (although I'm working on this) and it will be pushing out well over 400rwhp this season, maybe in excess of 500, so traction is concerning me.

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Old 02-03-2007, 09:25 PM
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when you guys go 255+ on the fronts, do you feel any "turn-in" disadvantage? also straight line speed?
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Old 02-03-2007, 09:43 PM
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Maybe, but hard to say. I've noticed a bit more initial understeer but I think that's more a suspension change than the tyre width. You get used to what you drive on so you would almost need to do a back to back comparison to tell the difference as far as I'm concerned. Others will probably know more.
I'd still love to know if anyone is running 315's on 11" under stock guards???
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