235/40/18
 

Are any of guys running this size on a 986 with a 7.5" front rim? I'm thinking about going a size wider up front to help reduce the low speed understeer the car has. If so, how is it working for you? Any problems getting them to fit on the rim?

I think tirerack lists the rim width range acceptable for the tire. If not, maybe the manufacturer will have the info.
It may have a clearance issue, but this would also change with different tires of the same technical size.
I went the other way, I have 8.5" wide front rims for that size tire (stock 987 front) and 10" wide rear with stock tire that was on 9" stock rim.
The reason I did this is tire stability. The wider rim restricts the sideall from flexing as much. The narrower rim will probably give more sidewall flex which, depending on individual tire, may increase understeer by distorting the tread or lifting part of the footprint.
Let's hope someone who has tried it sees this thread and responds!

I have the OEM 18" rims and am running 235/40/18 on front.
Fits fine and takes a little understeer out

Tire Rack has the range as 8-9.5 for a 235/40/18 but I'm not going to let that dissuade me yet. I know of some fellow Mazda autocross guys running a 245 on a 6.5" rim! :eek:

good good. Thanks Chris!

Actually when I ordered the size on tirerack I got a call from them on my mobile phone the next day, verifying that I really wanted that size. I then confirmed (and convinced them) and then they shipped it.

Pretty good customer service, ey?

That is good customer service. I have had nothing but great experiences with Tire Rack which is why I keep going back. :cheers:

I run 225/40/18 on the fronts and 265/35/18 on the backs. Just what you see here. Nice feel and handling...I do not performance drive at all...to old for that anymore. :cheers:

Yup, that's what I'm running right now as well. I got an alignment done last year and maxed out the front negative camber at a whopping .5 degree and it helped but it still has a propensity to push in slow corners. I'm just looking for an extra edge out on the autocross course. Since I run in stock class there isn't a whole lot I can do and still stay legal.

O Crap...you have a 6-speed. Wanted one myself, but settled for this old farts Boxster instead. Still fun to drive. :cheers:

LOL! Me too, old Phart that is, just turned 69 last Oct.

Now I have a wheel dilemma. I have a set of 8x18F & 10x18R five spoke Carrera Lightweights. I need to have them refurbished before they are presentable but they were cheap enough to consider getting them spruced up. Original Porsche wheels from a C4, '02. I am currently running the straight windmill spoke specific to the '01 Boxster, 7x17 F & 8.5x17R which I am fond of plus the width of tire still delivers decent mileage. What I wonder is what, if any, weight increase will be if I switch to the 18's? Cost of tires is a bit more expensive but not that bad. Any buddy have weighed their 18's for comparison? Also when you switched to 18's, did your mileage suffer?

AKL