I have an 86 GT with the Muncie 4 speed. want to swap out the factory 15 inch rims for 17's. I'm thinking this would gear it taller (a good thing with this 3800) and wondered if anyone can tell me how much difference it makes.

It all depends on your tire size. There wouldn't be any change if you used a lower profile tire. Do a search on Google, you can find tire calculators that will give you % of change.

~Tyler

Thanks, I found one that shows a 10% change with what I want.

Will they fit and not rub?

17's with the correct offset shouldn't be a problem.

My rear tires are 235/50/17 on Scion TC rims. I had to use coilovers but my speedo is off just a hair under 10% vs. the 215/60/14 I was running. It may not sound like much but with my Duke, It really helps having the RPMs lower when you're cruising at 70, which the speedo says is about 63mph. I haven't found a speedo gear that ill work yet' I'd like the right gear just to keep the odometer accurate and not be off by 10%.

I was planning on running 235/60-17's on the rear. I think I should be safe, but as low as a 215/60 wouldn't hurt my feelings any. I will not go to coilovers.