275 40 17 & 225 45 17 Tires

[Dwiggy]

Hello All!

I recently purchased my 99 C2 with noisy Goodyear F1s (Yuck!). I love the feel of Goodyears but I cannot live with the noise.

My favorite tires are Potenza RE960AS Pole Positions as they serve their purpose very well with a longer tread life. Unfortunately, Bridgestone does not make the correct sizes for 17 inchers.

In researching tires I came accross a new model of Continental called the ExtremeContact DWS. The DWS stands for Dry, Wet and Snow. The treadwear rating on these tires is a 540! The limited reviews as of yet are excellent and Continental offers a 50,000 mile limited treadwear warranty. So, before I buy...

I accomplished some calculations on my tire dimensions for your consideration.

OEM

Front Wheel 7.5"

Rear Wheel 9"

Front Tire 205/50 17

Height 25.1"

Section Width 8.5"

Revolutions 825

Rear Tire 255/45 17

Height 25.1"

Section Width 10.2"

Revolutions 825 (Current speedometer is 6% off from the factory)

NEW

Front Tire 225/45 17

Height 24.9"

Section Width 9.2"

Revolutions 828

Rear Tire 275/45 17

Height 25.7"

Section Width 10.9"

Revolutions 811 (Speedometer will be closer to 3% off)

As you can see the OEM (v) NEW widths are 7/10 of an inch different. The heights are a mixed bag with the fronts 2/10s taller and the rears 1/2 and inch shorter, OEM/NEW respectively.

DSWs will not be as grippy as the F1s because of the harder material and deeper tread.

Wider and shorter tires on the front should increase over steer a bit.

Wider but taller tires in the back should decrease over steer a bit.

The DSWs still have a rigid sidewall as they are Ultra High Performance but my ride should soften a bit because of the extra tread and width.

I am not sure if Continental will offer the DSW in the 255 ratio when I purchase these tires in the near future.

I do not AX this car and never intend to drive it any other way then normal on the street.

There is a post on RennTech that addresses this issue with regards to auto cross but there was no follow-up on the decision made by the poster and results.

Has anyone used the sized tires that I am considering?

Thanks,

D.

[Dwiggy]

This does not appear to be a popular topic. I'll post on the install in a couple of months.

D.

[Dwiggy]

To follow up on this post, I decided to purchase 18s with the appropriate sizes for 99.