My car came with 16" rims - but in an effort to look cool, I put 18" rims on.
Now, when I am driving and my speedometer reads 65, how fast am I really going?
2007-02-23 15:05:06 · 9 answers · asked by bluenbri 3 in Science & Mathematics ➔ Mathematics
ummmmm, well, about 73 miles per hour, judging solely on that, but it is the size of the tires, not the rims, that matter
2007-02-23 15:10:51 · answer #1 · answered by lifelesswonder 4 · 0⤊ 0⤋
you changed thing by a ratio of 18/16 (assuming the ratio of the heights of the tires is the same as the wheels).
18/16/9/8=1.125
when your speedometer reads 65 yo are going 65*1.125=73mph. Watch out for smokey!
2007-02-23 23:57:50 · answer #2 · answered by yupchagee 7 · 0⤊ 0⤋
The question cannot be answered with the diameters of the rims. You need to know the outside diameters of the new tires and the old tires. When you find that use the equation for circumference pi*rad^2 for both the new and old tires. Now you subtract the old tire circumference from the new tire circumference. I'm putting myself to sleep. I'm going to ballpark it and say you are probably traveling about 2 mph faster than the speedometer says.
2007-02-23 23:24:10 · answer #3 · answered by Anonymous · 0⤊ 0⤋
umm.. 65 miles/hour means 4 118 400 inches/hour, which means 4118400 / (2*pi* 16) = 40967 revolutions of the wheel per hour, assuming the original rims. But 40967 revolutions with rims of 18 inch radius means
40967*2pi*18 = 4 633 258 inches = 73.125 miles.
The speed and rim are basically proportional because C = 2pir is linear.. so you could say (18/16) * 65 = 73.125 miles p hour
2007-02-23 23:16:42 · answer #4 · answered by need help! 3 · 0⤊ 0⤋
The size of your rims does not determine how fast you go, just how much energy it takes to fully turn the wheels around a circle once. Meaning in simpler terms.. You buy more gas.
2007-02-23 23:13:28 · answer #5 · answered by Steve 2 · 0⤊ 0⤋
65*(18/16) = 73
2007-02-23 23:25:27 · answer #6 · answered by Anopheles 1 · 0⤊ 0⤋
You've increased the circumference by 1/8 pi which will also be your increase in speed.
2007-02-23 23:11:54 · answer #7 · answered by St N 7 · 0⤊ 0⤋
insufficient data
need respective circunferences of tires
need to know if speedo was accurate in the first place
best guess is about 68
2007-02-23 23:17:51 · answer #8 · answered by ? 3 · 0⤊ 0⤋
I really cannot answer this question but i think that the answer is 1/.4-.088
2007-02-23 23:16:17 · answer #9 · answered by ashleyprincess 1 · 0⤊ 0⤋