View Full Version : 205/40 x 17 Body and Suspension Clearance Values

04-30-2016, 02:31 PM
For the benefit of others, as well as for my own future reference and documentation.

I've just spent over an hour crawling all over and under my '13 Abarth Cabrio, measuring the clearance gaps between the inner edges and diameter of the tire as compared to "something" which could rub. This in an effort to convince myself that a 215/40 x 17 tire will, or will not, fit without rubbing against some part of the car, somewhere. Mesurements were taken at all steering angles, lock to lock, for the front tires.

Disclaimer: These measurements are for my car, which has the OEM 17" x 7" wheels and Pirelli P-Zero tires. They may, or may not, match the similar measurements for your own Abarth.

Side wall: The tightest clearance between the tire sidewall and a body or suspension part are pretty much equal, front to rear. For the front, I have an 11 mm gap between the side wall and the shock / spring assembly. At the rear, I have a 12 mm gap between the side wall and a suspension member.

Diameter: No worries at all for the diameter at the rear - there's lots of room. At the front, there is a clearance gap of about 8 mm between the tread and the plastic inner fender liner. This for a tire which has maybe 75% tread left.

According to info posted at the Tire Rack website, a new 205/40 x 17 Pirelli P-Zero has these dimensions:

Section width: 8.1"
Outside diameter: 23.7"

Based upon these numbers, I have concluded that, allowing for, let's say, 5 mm clearance at a minimum and which also allows for tolerance variations, the largest 17" tire that can confidently be fitted without rubbing would have dimensions of:

Section width: 8.57"
Outside diameter: 23.93"

Math below for posterity:

Closest width clearance gap = 11 mm. Back out 5 mm for tolerance = 6 mm x 2 for the overall width = 12 mm = 0.47" which, when added to the OEM 8.1" = 8.57".

Closest diameter clearance gap = 8 mm. Back out 5 mm for tolerance = 3 mm x 2 for the overall diameter = 6 mm = 0.23" which, when added to the OEM 23.7" = 23.93".

Happy tire shopping!

Cheers - DM