If I put larger diameter wheels & tires on my car will the speedometer be accurate?

Answer 1

depends on the size. I oversized my tires by 5 and it threw my speedo off by about 3 MPH

Answer 2

If u get larger wheels you will be going faster than the speed and smaller your speedometer will slower. One thing to look at is the factory wheels w/tires diameter. 15" tires are like 22+ inches tall so take into count that if you went from a 15 inch rim with say a 225/65/15 to a 20 inch wheel with a 225/35/20 you 20" wheel would be smaller then you 15". If you know what wheel and tire you will be using go to the tire website and find out how tall the tires are and then go to the tire website of the factory tire makers and compare...a inch diff wont make a noticeable change in speed...

Answer 3

Let's give an extreme example. Let's say you started off with 16 inch stock rims. Then, you decided to put 7 inch rims on the car for some crazy reason. Doesn't it stand to reason that at a given speed (say 55) that the 7 inch rim would rotate more times than the 16 inch rim because the 7 inch rim is so much smaller. The 7 inch rim has to spin more times to cover the same distance meaning that the speedometer and odometer would be quite wrong.

If you had a 1986 Acura Integra with stock 14 inch rims with 65 series tires and upgraged to 17 inch rims with 40 series tires your speedometer would be close because the overall "tire height" of both tires is the same.

You can always just buy the rims you and have the speedometer re-calibrated at a shop after you are done. Many new cars speedometers can be re-calibrated by hooking an aftermarket computer to the diagnostics ports. This computers can also be used to modify your engine performance for more power.

Answer 4

You have to step it up correctly to keep the over all diameter the same. Go to a tire/wheel retailer and inform them of the original tire size the vehicle calls for so they can accurately tell you the maximum sized wheel you can go with and keep your speedometer in check. If you go too big, your speedometer will read slower. If you go too small, your speedometer will read faster than what you are going. Go to a tire/wheel retailer, they should steer you in the right direction. Some even have computer programs that will show you how the wheel you like will look on your vehicle.

Answer 5

No. It will appear to be about 5 mph SLOWER than you are actually driving. (ex: if speedometer says 35 mph, you may actually be going 40 mph, and the police will NOT accept this as an excuse). Find a friend to drive along side of and prearrange a speed for him, say 35 mph. Then drive beside him and find out what you read. Try at several speeds. It should be constant, but you might as well be sure.

Answer 6

No, your cars speedometer will be off. I have the means of telling you how fast or slow it will be.I can also make the recommendations on what size you should put on. I need to know the year and kind of car and the factory tire sizes.

Answer 7

any change from the factory diameter tires(larger or smaller) will cause a difference in the speedometer.

Answer 8

no b cuz u need 2 buy a chip it a override that mess with the thign in the engin then it will say what size rims then u put in what size u have then it will give u the right speed your goin it cost from a 100 2 about 500

Answer 9

i'm pretty sure tha it will have to be adjusted. My friend's dad got larger tires, and was pulled over for speeding, even though the speedometer was at the speed limit.

Answer 10

If you keep the overall diameter of the tire/wheel combination the same, your speedo will have the same accuracy. If you go bigger, your speedo will read slower than actual, if you go smaller, your speedo will read faster.