does putting bigger rims throw off your speed i got 17" drag rims with 205-40-17 on a 90 hatch dx

 

yes you have more rotational mass so your speedo will be off. You actually go slower with bigger rims.

 

how do i find out how fast im going besides somebody following me

 

speedometer calibration

 

math

engine rpm times some reduction due to gearing based on the gear you are in and your final drive will give you a close approximation to the number of engine rpm to wheel revolutions you should see. If you figure out the rpm of your tires and then calculate the distance travelled per rotation, you should come out with a velocity in inches per minute, which is an easy conversion to miles per hour.

of course, you could just check out the FAQ section for gear ratio calculators.. but what fun is that..

 

http://www.1010tires.com/TireSizeCalculator.asp

 

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slower acceleration, but a higher top speed.

with bigger rims, you'll be going faster than what your speedo tells you.

 

 

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wtf does rotational mass have to do with speed??? OP, the vehical speed sensor measures how many rotations your wheels make over time to determine your speed. so if you change the circumference of the outside of the tire, you change how far your car moves with every rotation. and since speed is the distance traveled over time, your speed is going to chang along with that.

 

ok about 2 mph difference, i thought it was going to be bigger difference like at least 5 mph well thatnk everybody

 

17"s are wayyy too big for our cars man, go with 15"s and you'll thank me later