I compiled this a table of tire sizes vs. speedometer error for my tire selection and decided to expand and post it on the board for those who might be interested.

The data sources are Tire Rack.com and Tires-n-Wheels.com.

For my new 15x7 panasports, I'm thinking of Bridgestone Potenza RE960AS Pole Position tires. My use will be street and highway driving with the occasional, (maybe 2x yearly), fun-run autocross.

Any comments or suggestions?

Julio

1972 240Z (restoration in-process)

Silly question:

I know stock tire size is 175/14...but what is that in modern day standards?

I understand that your chart converts this...but just curious. Was the stock tire an 80 profile?

And why not include 195/55r15 on your chart Lots of good tires in that size

The old 175SR-14 would be a 175/78-14.

Thanks for putting this together Julio, definitely very helpful!

I am currently running the 960A Bridgestones. Good tire, with acceptable grip to have fun with. I enjoyed them at my track day all day with no real loss of performance. I finally found their limits when I spun at the end of my last 15 minute session.

I would really prefer a Summer tire. All seasons are just a compromise. But the 960's are a pretty good compromise. I have 195/60's on my Z on the new VTO's.