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Tyre Profile Size - Help Please

Hello
I have a 1999 Porsche Boxster. I have just purchased a set of new Wheels for the car and now I am looking at getting some brand new tyres fitted to them. What I would like to know is what size Profile tyres I need.

My wheels are F 18 x 8 & B 18 x 10

I would like to fit to the front 235 Tyres and the rears 285 Tyres. What I dont know is what profile I need on each tyre.

Thanks in Advance!!

C
H
A
S
P

Stick with OEM Sizes

Front 18X8 go with 225/40/18

Rears 18X10 go with 285/30/18

Thats the set up im running and I have 18X8.5Front and 18X10Rears they fit perfectly. Those sizes are standard on the 2004 911's with 18" Wheels

So 235 are no good? may I ask why (I dont know much about tyres sorry)

Did you have any problems fitting 285 on your boxster? They should fit mine fine?

Quote:

Originally Posted by CHASP

So 235 are no good? may I ask why (I dont know much about tyres sorry)

Did you have any problems fitting 285 on your boxster? They should fit mine fine?

Hi,

If you go 235 aspect ratio, you'll experience severe tramlining and poor wet traction and steering. Personally, I wouldn't do it...

Happy Motoring!... Jim'99

Quote:

Originally Posted by CHASP

When deciding on plus size tires it is important to determine the diameter of the new wheels. It is important that the wheels are not too big for the wheel wells or result a higher or lower rides. I have seen so many ugly setups where the cars ended up looking like carraiges because the wheels are just too tall. Another reason to ensure that the speedometer and techrometer remain accurate or very close. The stock tire sizes for 18" on boxster are 225x40x18 (front) and 265x35x18 (rear). The following link can be helpful deciding on the apprpriate plus size tires:
http://www.miata.net/garage/tirecalc.html

Good Luck

I am going to go 225/40/18 on the front and would like to go 285/??/18 on the rear, I think the profile for the rear's we be either 35 or 30. Has anyone else got 285's on there boxster?? If so please post whats needed it any

Quote:

Originally Posted by CHASP

It has to ben a 30 series as Porsche Reccomends. The 35series will be too tall. Just as a side note, the rear wheel offset will also play a part if you can fit a 285. What is your offset?