switching to Bigger Wheels

My car has 16 inch wheels on it right now and I am about to order new wheels but I am debating whether to get 17's or 18's. If I get 18's wont i need to have my speedometer recalibrated? This wouldn't be such a big deal if it was just a one time adjustment but i would like to be able to switch back to my old wheels in the winter because i will be getting chrome. That would mean having the speedometer recalibrated everytime i switched back and forth. Does anyone know of something i can do-for example smaller tires or something?

LOL, exactly, the circumference of the two tires will have to be the same for the speedo to be right. C=diameter*Pi... so the diameter of the Rim, plus the tire needs to be equal, for example, 16's with a tire 2" high is the same as 17s with tires 1" high.

you should look for a Jet SCU2000. Several sites still sell them... and theyre not too hard to find used on most message boards. it lets you reprogram the computer for gears/tires fixing the speedo and shift points.

about how much do these things cost?

I got my stuff reprogrammed at ACDelco for $75 after I went from 3.08s to 3.42s on my v6

i paid less than that for the scu used...

wish I was U