Newbie Tire size question

[TriGem2k]

I think a 275 will be a little sloppy on a 8.5" wheel.

[Sammy]

I'm running a 245/275 setup with Kuhmo V710's on 17x8.5" wheels. The 275 is a stretch for the 8.5" rim but I am truly impressed with the difference in handling. OMG does the car stick! I don't use spacers but it is a tight fit in the front. The rear could be spaced out a little but I'm not planning to do this because I'm thoroughly impressed with the handling at this point.

[AddictionRacing]

Originally Posted by Sammy

I'm running a 245/275 setup with Kuhmo V710's on 17x8.5" wheels. The 275 is a stretch for the 8.5" rim but I am truly impressed with the difference in handling. OMG does the car stick! I don't use spacers but it is a tight fit in the front. The rear could be spaced out a little but I'm not planning to do this because I'm thoroughly impressed with the handling at this point.

Do you have 8.5" all the way around or are the fronts still 7.5"? It sounds like I should try the 245/ 275 set-up. Thanks for the help, and please keep it coming if you have a different opinion. Once I make my decision and get them mounted up I'll share the results.

[kyle986driver]

From my experience with 205/16 and 245/16 hankook RS2s, I wish I had done equal wheel and tire sizes all around. For me, I dont have a HUGE selection of matching tires, and few R-comps are made.

I believe most of the national guys run equal sizes.

hope that helps.

[Sammy]

Originally Posted by AddictionRacing

Do you have 8.5" all the way around or are the fronts still 7.5"? It sounds like I should try the 245/ 275 set-up. Thanks for the help, and please keep it coming if you have a different opinion. Once I make my decision and get them mounted up I'll share the results.

I have 8.5" all the way around. I'm not sure a 245 will fit on a 7" wheel but do some searching to find out if anyone has done this? You might also search the following site:

http://boxcar-racing.com/forum/index.php?PHPSESSID=16734c86c80c5b091424f4403ffd2c 66&

In terms of grip I found that between the new tires (granted it could be the compound of the V710's) and the lower stress bar I was dead even with a couple guys that I was 2-3 seconds behind last year. It was a little weird getting use to virtually full throttle through the slaloms. The car was very neutral and much more predictable than before (of course this could be my driving style?).

[renzop]

First off a 245 will fit on a 7" rim no problem.

Second. The Boxster understeers in slow speed stuff like on an autocross course, so you need to change the balance between front and rear grip with proportionally more grip on the front. The best way to do this is by increasing the front tire width relative to the rear.

If you were only going to autocross on them then I would go with 255 all around. But that combo will be a little tail happy at high speeds. For a tire that you are going to street drive as well then I would recommend either
235 f / 255r
or
245 f /255r

Looks like Falken makes a 235/17, 245/17 and a 255/17 in the ST-615. By the way, the ST-615 has very little hydroplaning protection; be careful in the rain!

Regards,
Alan

[AddictionRacing]

Originally Posted by renzop

If you were only going to autocross on them then I would go with 255 all around. But that combo will be a little tail happy at high speeds. For a tire that you are going to street drive as well then I would recommend either
235 f / 255r
or
245 f /255r
Regards,
Alan

Alan,
You mention 255 all around strictly for autocross use and 245/255 for street/autocross. Would a 255/275 set-up work? I assume to do this I would need to get another pair of 8.5" rear wheels to use on the front. Does the stock rear offset work on the front? (Othrwise, I know it would be quite a stretch, but do you know if it would be possible to stuff 255s on the stock front 7.5" wheels?) Thanks again to everyone for chiming in - very much appreciated.

-Matt

PS - I'm going to pick her up tonight!! I can't wait!

[stcroixdrew]

I am running Falken FK-452's..235 40 zr18 & 265 35 zr18 on my 98 Boxster....they are great in the rain and have fantastic Auto X traction.....for the $$$ I would highly recommend them.
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