I've clocked many miles with my 205/70/14's, and they read about .75 mph slow at 70. I'd use the paspeedo calculator to determine what is closest to that size. What kind of rims did you get? I've been looking for a set of steel 15-incher's with the correct offset........I'd like to do the trooper look; black wheels with bottlecaps, no beauty rings.

Ok, here's the resultant diameters (only theoretical, obviously there are many real-world circumstances which will cause different numbers):

185/80R14 - 25.65"

185/75R14 - 24.93"

185/70R14 - 24.20"

205/70R14 - 25.30"

195/60R15 - 24.21"

205/55R15 - 23.88"

205/60R15 - 24.69"

205/65R15 - 25.49"

Based on the overall circumference, you can do the math using transmission and differential ratios to determine gas mileage and other stuff.

I admit I'm not an expert on this, but I thought 240s (non-turbos) came with 185/70R14s. And of course, turbos came with 195/60R15s. Look at how close the diameter of the 185/70R14 is to the diameter of the 195/60R15.

"Not sure if I should select a 205-65R15 or a 205-60R15."

Well, the 205/60R15 would probably be closer to the original diameter. Also, 60-series tires may be cheaper than 65-series, due to 60-series being made in larger quantity (a supposition on my part). However it is my belief that the 195/60R15 would be closer to the origianl 14" tire diameter.

I'm now running 205-60's, but I've also used 195-65's; they're both only a few percent different than stock, within speced tolerance for any of the sizes.

Look at the info available at www.tirerack.com and www.paspeedo.com.

If the stock is between 75 and 80 (mine is 75), then it should be closer to 205-65, right (as a 75 translated to 15's should be ~62.3)? At any rate, 740's with 15 inch wheels come wiht 185-65's. whichever you go with, can you keep us posted with how they come out? been thinking similiar things myself...