More dumb questions from this noobie.

Hey, do you guys think that the additional rotating mass, going from 15inch rims to 18 inch rims will make my car feel slower?

Also, what will happen to my speedo? On my older car you had to get a new part to replace the old speedo, but I don't know if the Audi uses a digital speedometer sensor or mechanical or what. Typically larger tire means your speedo will be off.

Anyways, everything I ordered just shipped out this morning and I got my tracking numbers, very excited!

 

No you most likely will not feel a difference (or if you do it will be in your head like with your new muffler)

If you compensate with thinner tires (which you should), your speedo will be off slightly but not enough to make a significant difference ( couple mph). The amount you will be off depends on the overall difference in size of your current wheel/tire setup with the new setup.

Good luck with everything, I look forward to seeing the changes on your timeline.

 

http://www.miata.net/garage/tirecalc.html

This helps. A lot.

 

That's awesome man, thanks so much, bookmarked. Looks like the 235/40-18's won't be much of a problem on the speedo at all.

 

Jeremy (ImTheDevil) gave me that link a couple months ago! It's awesome but I still haven't decided on a tire size yet .

 

Get 18's like everyone else.

 

ok, he is right in the fact that if the overall circumference is the the same your speedo should be fine... now for the rotating mass/unsprung/sprung weight making the car feel slower... look at mikes car, he doesn't run 18's on his "race" car... and it is for a reason...


yes the car will be slower, by how much maybe not alot, but it will be slower... if you are fairly stock, which i am pretty sure you are..... it might make a difference

 

Very stock, and I know it makes a difference when you lift a truck really high and do no power mods, so I assumed the same would apply. I also know it will decrease braking because of increased sized. But I plan on a brake upgrade.

 

I will stick with my 17's thank you very much!

 

A general rule of thumb I use is decreasing the sidewall # by 10 for every inch of rim that is increased. So I'd go from 16/55 to 17/45 to 18/35. That generally gives you about the same diameter. Some tires are designed a little different though so it won't always be exact. As for the rotating mass thing, I think the weight in general of the rim added to the car is what would affect how the car performs. Remember that the car's power is moving the weight of the whole car, not just the rims. So if you put some big old 20" steel rims on your car, of course it'll weigh the car down more.