I know they can be put on there with no fitment issues. How do you adjust the speedometer for ther 5% diameter decrease? Is there a gear that I can pull from a legacy GT or 2.5RS and slap it in in 30 minutes time?

 

You are probably just going to have to deal with the speedometer being off. Changing gears in your transmission will take much more than 30 minutes.

 

If anyone could explain how to gain access to it, it'd be appreciated. I know in some cars it's quick, some it's lengthy. But no car have I seen it necessitate major transmission work.

 

I've never heard of anyone changing speedometer gearing when changing tires...

 

Oh, I misunderstood. By gear I thought you meant tranny gear, but that didn't make any sense. I get it now, too early in the morning I suppose.

But like DLC said, I've never heard of people doing that for a minor tire size difference. I'd just as soon keep in mind that my spedo is reading about 5mph lower.

 

Put a different size tire on so your overall diameter stays the same.

 

You have to open the transmission case to change the speedo gearing; I'm not sure just swapping out the sender will do the trick. I've run on a few sets of RS and WRX wheels with the shorter tire height on my OB, and your speed will show you going about 7-8mph faster than you actually are at ~65 (actually doing 58).

Honestly, it's not worth messing with, as the speedos are off a little bit when stock anyways. I eventually swapped to a JDM 4.11 transmission from a 250GT and the new sender/gear gave me the correct speedo reading, but it was just a bonus, never something I'd pull the tranny for.