hey i have been a member of this site for about 2 months and i have a 97 ford probe base model. i want to get a set of the gt factory alloys for mine and was owndering if it would play with my speedometer or anyting else and anything elseon the car. thanks for any advice anyone can have on this question of mine rage

Just make sure that the overall diameter of the rim with the new tires isn't larger then the old rim and tire. And if anyone is interested, I have a set of brand new SE rims that I got from the dealer for sale. They came off a 95 that was never sold... I am only asking $200 for all 4, nice to have for the winter!!!!!! JSpeed

Your probe has 205/55-15 tires on it right? Well if you went to the GT wheels, you would be using a P225/50-16 which would make your speedometer 4.10% too slow. If you have the 195/65-14 the speedometer would be 3.66% too slow. Of course if it affects your speedometer its going to affect your odometer. Other than that, nothing else should be affected, those wheels will bolt right on. If you want to see where I got those numbers or just a visual representation of how much bigger the wheels are check out this link: http://www.miata.net/garage/tirecalc.html Dedric Ramsey dedric@...

I too replaced my 15" rims on my PSE to the 16" PGT rims. In doing so I also had a change in tires. I went from the 205/55-15 to 225/50-16. The new tire/rim combination adds almost exactly 1-inch to the overall tire diameter therefore there will be a difference between speedometer reading and actual speed. The % difference between speedometer and actual speed Dedric listed are quite accurate. However the TRACK (distance between left and right wheels) increased slightly and affected the alignment by putting more negative camber. The amount of negative camber was slight but substantial and was easily corrected when I got a 4-wheel alignment. A more practical translation of the difference between the speedometer and your actual speed will be that for every 25mph you see on your speedometer, your actual speed is 1mph faster. Example: 25mph speedometer = 26mph actual; 50mph speedometer = 52mph actual; 75mph speedometer = 78mph actual...etc. This really hasn't affected me or my driving much at all. Only time it comes into play for me is when I'm using cruise control (which is rare). If I want to cruise on the freeway at exactly 65mph I have to set it so it read 62.5 mph on the speedometer. -Lino Sacman

I have a write-up on this in on my web site. It's under the HELP section. If your browser can read VBScript I have a calculator to so you can look at different tire sizes. Check it out. probenet.tripod.com Enjoy, Bryan Pendleton probenet.tripod.com >

Out of curisity why can't you just buy a tire for the 16" rims that will match up height wise to the 14"s or 15"s your Base has? Then you wouldn't have any mph or odometer problems. Are there no tire sizes that will let you jump from 14" or 15" to 16" keeping the same height? I had no problems finding an almost exact match for my stock 15" tires for my new 17" rims... 205/40 - 17.

did u loose power with the bigger tires/rims?

He can, but there are a couple of things to consider. First, you have to determine the size that will have the least possible affect on the speedometer, that part is easy. Then you have to find a tire in that size assuming the size is readily available, and that the tire will fit on the rim safely. Going from the stock 205/55-15 to 205/40-17 causes a small amount of error (1.7%), but 215/40-17 is even better with .4% error. If he's using the 205/55-15 and goes with the gt rims, he could use a 225/45-16 and do even better with a .3% error. This size has a pretty good selection of tires he could go with (Id recommend Yokohama A520's. They are good tires wet or dry, and only cost $116 a tire! You cant really beat the price/performance ratio here, and they get good wear too.) If you dont want to go to 225, you could get 215/45-16 and only have 1% error, which still is pretty good, its not off much. As far as the fit goes, all of those tires should fit with no problem, but I dont know how anything smaller than 215 will do on a 6 inch rim. Good thing about the base/SE, seems pretty easy to find tire sizes for +1 +2 upgrades that keep the spedo in check. P.S. If you have the 14" steel wheels, the 225/45-16 are a near perfect match, .03% error, plus instantly looks better. :) P.P.S I found a good page a while back with some real good information on this very subject, check it out: http://www.voicenet.com/~coughlin/dsm/twheel.htm Dedric Ramsey dedric@...

I didn't notice any power loss with mine... stiffend the ride up alittle bit,made so you can feel more of the road & it improved the handling. As far as how close they are to the factory tires... I have no idea how to figure out the ratios and no desire to try, the shop I got 'em from said they would be a really close match. And before I put 'em on I set them next the factory ones and my new 17"s were taller only by about 3/4 the tread depth and since the old ones were almost beyond bald I figured they'ld be close enough I'ld never tell the difference... and I haven't.