PeachParts Mercedes-Benz Forum - View Single Post

G-Benz · #2 06-14-2001, 12:08 PM

There is a thread on the "Wheels & Tires" forum that outlines the calculation for tire sizes.

Basically, the 75 (or 70) is the percentage of the sidewall diameter in relation to the width of the tire. So for a 195mm width, a 195/75/14 tire has a sidewall height of 195*0.75=146.25mm, vs 195*0.70=136.5mm sidewall height. That's about a 10mm difference.

Add that to the wheel diameter, and you can figure out how much more tread perimeter the 195/75/14 is to the stock size.

Basically, you have a larger tire, and therefore, your speedometer readings will be a bit on the slow side. I didn't go through the entire calculation, but I would guess you would be off by 2 or 3mph when going 60 of more.

I go through this a lot with the Beetle. I am always having to figure out a new tire profile to purchase, as the current profile gets discontinued...