Just got 03' Denali wheels, how fast am I going?

[dakotarota]

My speedo is set for my 16's & now I have 17's. How much faster am I going??

[Shaners]

I bet you are about the same... I don't kow what size tires are on the Denali wheels, but I'm sure they have a lower profile sidewall, and that the overall diameter is pretty close to what you had before.

[Greg]

Enter your old and new tire & wheel sizes into this tire calculator and find out:

 

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

[Mr Mojo]

Wheel diameter won't affect your speedo, the tire size will, use the calculator in the above post to see if you are off at all.

 

For example, I run a 275/40R17 on my vette, but for racing I put on a 275/50R15, they have the same width and overall diameter, the only difference is teh rim size.

[Ben]

Ditto that it's the tire the really matters for speedo/computer readings.

 

Not just dia, but better to use rev's per mile, as not all tires squirm/roll the same.

 

The percentage difference in rev's per mile will be the amount off by on speedo & diff ratio.

[BlackTaz]

And if you want to prove it to yourself... take a stopwatch on the freeway and set the cruise for 60 MPH. If it takes you 60 seconds to go a mile, on average, over a few miles (use the markers on the freeway), then you're right on. If it's taking you a few seconds more, or less, you speedo is a little "off"... probably due to your tires (but could be other things).

[Wingnut]

Well....If his speedo is off, then his odometer wouldn't be working very close either.

 

And I wouldn't trust the mile markers. I have used GPS, and seen that they aren't all that accurate.....Yeah....I was really bored that trip.

 

Of couse, the above trick would work with GPS....But then, GPS will tell you how fast you are going without the math anyway.