calvani

Hi Folks,

I am in the process of getting tires for an '01 Boxster. The wheels are 18x18 ET45 mm front and 10x18 E40 mm rear. The recommended tire size for these wheels are:

Front: 225/40/18
Rear: 265/35/18

My question is: Can I go with 285/30/18 in the rears w/o any problems? Is the car going to look funny given the lower profile of the rear tire? What if I stick with the same recommended profile but use 285/35/18 instead?

If I want to go with 285s in the rear which profile height do you guys recommend?

This Boxster has not been lowered and it would only be driven in the street.

Any advice would be greatly appreciated...Thanks in advance!

Humberto-

bruinbro

It sort of depends on tire brand. All 285's are not created equal. Do you know which brand(s) you are considering?

Bro

Q

calvani,

- Yes you can go 285.30.18's without a problem. [although I did fit GT3 5mm shims to allow them to clear my coilovers]
- The car looks better WITH the 285's ....[received lots of "looks tough" comments]
- 285.35.18 will look stupid.....like tractor tyres. It will also make your speedo inaccurate.... reduce your acceleration.....

Some other issues to consider:
- using 285's increases the cars understeer noticeably !............I had to dial in as neg camber as possible to counteract it.
- using 285's increased the unsprung weight of the rear end considerably.......It made the car unpleasant on rough roads
.....still didnt stop me using them though

BOTTOM LINE:
- if you prefer looks, go the 285.30
- if you prefer handling, stay with 265.35

Cheers
Q

calvani

Bro, I was considering to put Bridgestone Potenza S-02 tires if I go with the 285/30/18. If I stick with the recommended size on the rear, 265/35/18, the
Yokohama AVS ES 100 seems very attractive (A four-star tire for $185/tire in
www.tirerack.com).

Q, thanks very much for all the feedback! This is exactly the information I was after, and it should prove to be useful to other Boxster owners in the Forum.

Given the pros (awesome looks!) and cons (affects:understeer/handling, more weight, higher price) of the 285/30/18s, what do you think of compromising with 275/35/18 ? Yokohamas AVS ES 100, which are great tires, and are available in this size are for under $200/tire....(they don't make 285/30/18).

Thanks again.

Cheers,

Humberto-

mdex

I would stay with the 265's. Unless you are putting more rubber on the front of the car to balance things out it isn't worth upsetting the handling balance of the car IMHO. If the rear tires aren't filling out the wheel arches you can always put on spacers (I have 15mm spacers all around on the car)

Marc

Ray S

+1

265 is plenty of rear tire for the Boxster. I find that my car has good balance with a 235/265 combo. FWIW, I have 265's on 10" wheels on my car for the street and 265's on 9.5" wheels for the track.

calvani

Marc, Ray, thanks for the comments.

Ray, are those RH wheels on your red Boxster? Nice wheels....

Humberto-

Ray S

My street wheels are Gemballa Competition 18's and my track wheels are BBS RS GT's.

bruinbro

235/40 and 295/30 MPSC's on 8.5 x18et50 and 10.5x18et40 rims.









Bro

Ray S

I don't know.......that sounds like a recipe for rubbing and understeer.

I'd think you would need a ton of rear camber (more than you'd want for the street) to keep those rears from rubbing. How does it work on your car?

calvani

Thanks, Bro...

That's a quite a set-up! Are you using spacers (then again, you do have ET40 mm offsets in the rears)? Are those Michelin Pilot tires?

How does the car feel/handle with that set-up?

Cheers,

Humberto-

bruinbro

Fairly good on the street. I had to roll the fender lips and use JIC coilovers to get enough camber to prevent rubbing. It's a fine line that I walk on the street, though. I have just enough camber to prevent rubbing, but not enough to prematurely wear the tires on the inside (ask me how I know).

On the track, the camber is maxed out and the car handles perfectly. Oddly enough, I haven't changed out the sway bars. I think the reason this works is that the cage (when I had it in) stiffens the car significantly which prevents body twist and bending induced suspension geometry changes which the sway bars are sensitive to. Instructors and other drivers that are way better than I am have told me to not change a thing. I have the car dialed so there is negligible temperature differences across the faces of all 4 tires. It's kinda fun to watch the good drivers roll up the 996TTs and Vetts in it. Something that I aspire to.

Bro

bruinbro

No spacers as I do have 40mm offset rims. The spring perches for the coilovers had to be modified to change their location to prevent interference with the wheel rim.

The tires are Michelin Pilot Sport Cups. See my other post for a handling description. The ride is not what I would call smooth on roads that have holes, tar strips or have buckled slightly due to temperature changes and/or truck wear. But then, this is a compromise car and I have modified it to be as such. I like it.

Bro

Q

bruinbro,
I am guessing you have been asked this before....but talk to me about your " hardtop"
Looks wild !

Charlie C

I'm also curious about the rear. Does the top require removing the original trunk lid?