Oversize Tire Conversion for accurate mpg?

[Gary R]

Does anyone know of a thread or website that quickly allows you to convert oversize tire size to "standard" size tires for accurate mpg?

[trbankii]

Do you mean an online calculator that will give you the difference so that you can calculate mpg? Or do you mean a ratio converter to adjust your speedo/odo back to correct?

[Gary R]

I think an online calculator would work fine.

[trbankii]

Here is one that calculates the speed difference:

http://www.4lo.com/calc/gearspeedo.htm

From that you could get a rough calculation for mileage, although it isn't quite that straightforward since you're also figuring in increased rolling resistance, wind drag, etc...

[NutNbutGMC]

Here is one that calculates the speed difference:

http://www.4lo.com/calc/gearspeedo.htm

From that you could get a rough calculation for mileage, although it isn't quite that straightforward since you're also figuring in increased rolling resistance, wind drag, etc...
Correct indeed. However, an Excel sheet formulated with records keeping would be a one-time effort up front.

I find rolling resistance calculated in estimates for earth work or transport jobs. I doubt miles divided by gallons are inclusive of RR or WR factors for the average Joe like me.

Thanks for the link.

[jbplock]

Does anyone know of a thread or website that quickly allows you to convert oversize tire size to "standard" size tires for accurate mpg?

Here's one that works well ...

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

:)