From: darling@simlab.arc.nasa.gov on behalf of Dave Darling [darling@simlab.arc.nasa.gov] Sent: Tuesday, March 23, 1999 9:30 AM To: Tim Edwards Cc: 914 Subject: Re: [914] What's a 185SR15 tire nowadays? At 11:15 AM -0800 3/23/99, Tim Edwards wrote: >I'm trying to get an accurate tire circunference for gauging the correct >size for my new wheels/tires. My haynes book calls the stock 914 tire a >"185SR15". What does "SR" mean in 70/60/55 type aspect ratio nomenclature? >Anyone know? AFAIK, the stock size tires for all the four-cylinder cars were 155SR15 and 165SR15. The older tire nomenclature, where no "aspect ratio" is specified, assumes a "78" aspect. 80 is generally close enough and is a bit easier number to crunch. At least, those are both what I've heard as "common knowledge" on the various e-mail lists. You can check for more info on the tire size numbers--not sure if they say anything about the older no-aspect-nubmer nomenclature or not. Oh, and keep in mind that the tire sizes are only a general guide. Most tires will differ somewhat in diameter than the numbers you calculate. The best guide is the revolutions-per-mile figure that most manufacturers state. >Also, I'm contemplating using 15x& or * steel wheels in place of my EMPI >8-spoke knock-offs. (Discovered air bubbles in the metal at the lug pad >and don't feel comfortable with my V8 on that kind of shoddy casting). Sounds good. I know several people who have and still do autocross on big steelies. (Those are 7 & 8, right?) Heavier, but a whole heck of a lot safer than poorly-cast alloy wheels. --DD Dave Darling 74 914 2.0 (VROOM!) darling@simlab.arc.nasa.gov <--- OR ---> ddarling@wgss.com "914: The Porsche Picnic Basket. A lid that opens on each end, and a handle in the middle.." -- CHD