Newbie Tire size question
 

Hi All - I'm so new to the Boxster scene that I haven't even picked my car up yet. Thursday is the day. :D I am an autocrosser and want to put some wider, stickier tires on the car than it currently has and am wondering what the widest tires are that I can fit on the stock 17" rims on a stock 1999 boxster. As I'm sure you're all aware, the stock sizes are 205/50-17 and 255/40-17 but I was thinking 225/45-17 and 275/40-17 Falken Azenis 615s would be better. Does anyone have experience with this or a similar set-up or have a better idea? Would these fat guys even fit on the car without rubbing (without rolling the fenders)? Thanks in advance for your help!

Addiction,

My autocross buddy just put 245/275 setup on his 17" x 8.5" stock wheels.

( I believe he went with Kumho Ecsta V710's )

He is not running spacers and they seem to fit fine :

http://986forum.com/forums/showthread.php?t=15609&page=1&pp=20

( see Sammy's posts )

Hope this helps...

Nick

Thanks Nick - That is very helpful. Eventually I'll get a 2nd set of wheels with R-comps, but first I need to unload the old car (Jetta) along with the 5 sets of wheels I've accumulated for it.

I am running 275/35/18 on mine but I am not on stock, I have 18x10.5 on the rear. 275's work but you may need to roll the fender if you decide to drop the car

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

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.
:cheers:

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.

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.

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?).

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

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! :D

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.
http://www.cardomain.com/member_pages/show_image.pl?bg=FF6600&image=http://memimage.cardomain.com/member_images/10/web/2974000-2974999/2974869_80_full.jpg

The first autocross
 

I got the car last Thursday, the night before my birthday. I got up early to register it on Friday morning and got through the DMV in 13 minutes - not bad. I washed it in the rain, dried it in the garage, threw a couple coats of wax on it, and drove it in the rain out to my birthday dinner with friends.

Saturday was my first autocross with it, and I took 4th place out of 13 cars in the Street Tire indexed class. Not too shabby. Sunday I ran with the CT Valley Region PCA and took first place in C Stock - fastest Boxster of the day. Here are a couple of pics from Saturday (click for bigger images):

http://img383.imageshack.us/img383/2...md6xxg1.th.jpg
http://img383.imageshack.us/img383/8...gbn6vy0.th.jpg

RE: The first autocross
 

That's great! Are you just on the tires that came with it or did you buy the Azenis?

For autocrossing there is nothing wrong with stretching tires a bit on rims. For example, I have done 225/45/15 Hoosier A6 on a 6" rim and am currently running 245/40/17 on a 7" rim. Both were fine although you do have to find a shop that has good experience doing tough mounting. I also know a guy that is putting 285/30/18 Hoosiers on a 987 front rim - that's a 285 on an 8" rim.

That was just on the Toyo Proxes T1Rs that came on the car - 205 in the front, 255 in the rear. I just got the car back from the shop with a $1600 repair bill for the 60k service, spark plug tubes and seals, and front brakes, so I'm going to wear out the Toyos before spending the money on the Falkens. The Toyos really aren't that bad at autocross and I love them on the street.

Thanks again to everyone for their advice and input. I've decided to go with 245 and 275 Falken Azenis 615s when I kill the Toyos.

Update
 

I changed my mind and decided to get a second set of dedicated autocross wheels and tires. I got a set of 710s on stock Boxster wheels - 245 front and 275 rear. I love the set-up on higher speed courses, but on the really tight stuff there is still significant understeer. Probably the best part, though, is that no matter how hard I try I can not break the tail loose. The rears are just that sticky.
Thanks again to everyone who chimed in - it was very helpful.