Ex. My car came stock with 17 inch wheels. I changed them to 20 inches. My friend says this will affect how the speedometer calculates speed. I say it doesn't change it at all. Who's right?
2006-11-26 13:12:22 · 24 answers · asked by aznghetto456 2 in Cars & Transportation ➔ Other - Cars & Transportation
Your friend is right. Every inch will change the speedometer 2 to 3 miles per hour. So a 3 inch growth in diameter will probally increase your car's speed about 8 miles an hour over what your spedometer says.
2006-11-26 13:16:32 · answer #1 · answered by Ryan O 2 · 0⤊ 1⤋
Tire Size Speedometer Change
2016-11-04 23:48:05 · answer #2 · answered by Anonymous · 0⤊ 0⤋
The only thing that will change the speedometer is the outermost circumference of the TIRE. As long as the tier/wheel combination has the same circumference there will be no change. Example....if you are running say 32/10.5/r-17 and go to a 32/10.5/r-20 there will be no change. but if you went from a 32 to a 35...then yes, you'll need a speedo-gear change.
You can change the size of your rims, but have to keep the tire to the same outside circumference. A taller or shorter tire will change the speepo, NOT the rim. The speedometer and trans are calibrated to the specific distance that the outermost part of the tire rotates within one revoltution. If the tier travels 9 feet within revolution, it does NOT change the hub speed. But if the tire now travels 9.5 feet, it will change. It's the outermost measurement of the tire!!!!!!!!!!!!
a 25' tire with a 15inch rim travels as far as a 25inch tire with a 20inch rim!!!! The sidewall of the tire is where the measurement changes...... NOT the outside. The car doesn't care what size rim you have, as long as the tires height is the same as stock!!!!!!!!!!!!
The fact that all tires come in sizes to accomodate different WHEELS should be a clue. the wheel goes in the tire. the tire touches the ground. the whole thing goes around.
2006-11-26 13:16:40 · answer #3 · answered by FRANKFUSS 6 · 0⤊ 1⤋
It will affect both the speedometer and the odometer. If your wheels are bigger, there's more surface area that will be covered (more ground covered) for each revolution of the wheel. So each revolution of the wheel will take you a longer distance. So your speedometer will say you're moving slower than you actually are, which could get you into issues with speeding tickets and driving at a speed that's unsafe for the conditions.The car will have been calibrated according to the stock wheel size, so changing them without having everything else recalibrated will cause errors.
2006-11-26 13:19:03 · answer #4 · answered by wynterwood 3 · 2⤊ 0⤋
yes it does affect the speedometer. You need to stick with the same size tires that is recommended for your vehicle if you want to know just how fast you are going.Get a mental picture of a big wheel and a little wheel. The little wheel will have to spin faster than the big wheel to cover the same distance. So in turn your speedometer could possibly show you doing 45 mph. when actually you could be doing 50 or even 60 mph. on a radar gun. So yes your friend is right.
2006-11-26 13:19:57 · answer #5 · answered by martin1170_2 2 · 2⤊ 0⤋
This Site Might Help You.
RE:
Does a car tire's size affect the speedometer?
Ex. My car came stock with 17 inch wheels. I changed them to 20 inches. My friend says this will affect how the speedometer calculates speed. I say it doesn't change it at all. Who's right?
2015-08-18 14:30:36 · answer #6 · answered by Malkah 1 · 0⤊ 0⤋
You both might be right! It depends on the circumference of the tire, - not the size of the wheel! The speedometer reads the same (speed of the engine to gear ratio of the diferential) as it always did, - however if the circumference of the tire is different, then the tire (&wheel) will turn more, - or less revolutions per mile! Depending on wether its is smaller or bigger!
Now, - a lot of these "sporty wheels" have tires that only have about 1 1/2 inches between rim and ground - as compared with the "old normal" wheels, -- which have 4-6 inches clearance between rim and gound! So both might have the same actual circumference! ....Visualize two circles exactly 2 inches in diameter,----now draw a circle inside each one, -- one circle 1 3/4 inches, - and the other one 1 1/2 inches, -- which is bigger on the outside (circumference)?? This is what your two wheels and tires could look like visually!
Personally you couldn't make me put the 20" Aluminum "thin spoked" ones on my car,- (except with a "gun in my back") They look sporty and "hot" for sure,-- but they make the car ride like a lumber wagon! And this is an unwarranted expense to make the car ride in that manner!
2006-11-26 13:33:00 · answer #7 · answered by guess78624 6 · 0⤊ 0⤋
Anything departing from the MFG.s recommended tire size is
going to affect your speedometer's accuracy noticeably.
2006-11-26 13:28:26 · answer #8 · answered by huppercupper 3 · 0⤊ 0⤋
your friend is right.the speedometer is set to be accurate with the amount of rpm's your 17 inch tires made. Now you are going faster than the speedometer says. I know this for a fact because I got pulled over for this in my SUV after putting on larger tires than it came with from the factory.
2006-11-26 13:16:25 · answer #9 · answered by I know, I know!!!! 6 · 0⤊ 1⤋
When you increase the diameter of the rim, you must decrease the diameter of the tire. If you do not decrease the diameter of the tire, the overall diameter will be bigger.And by the circumference equation, C=Pi * diameter, any increase in diameter will increase the circumference. And therefore, will increase the distance traveled per revolution. This will make the speedometer display less than the true miles per hour. So, your friend is right :)
2006-11-26 13:18:24 · answer #10 · answered by Goddess of the Moon 3 · 0⤊ 1⤋