Updated Tire/Wheel Calculator

[Black Cobra]

This type of calculator has been around for over ten years I think.

Version V90:
I added a wheel and fender to it.

** Newest version is v91 **

TireWheelCalc091.xls

V91 Updates:

Added a line for a wheel spacer
Updated the "Other Section" with "From Hub Center"
Replaced the "Speedo" line with a Gears vs RPM vs Speed section.
Removed Ride Height change [The calculator I modified had lowered the Hub center to simulate some weight on the tire
"squashing the tire" yet left the full height "diameter" in tact...the car weighs zero now
Difference in Radius should be close to ride height change. ]

 

[gat0r]

nice, thanks

 

[Taz]

Sweet. Nice visuals to go with the calculations.

:thumbsup:

Just one thing. I think "Speedo MPH" should be Road Speed. The larger diameter tire requires fewer revolutions per mile, so the speedometer will actually read lower at the same MPH.

 

[Black Cobra]

Sweet. Nice visuals to go with the calculations.

:thumbsup:

Just one thing. I think "Speedo MPH" should be Road Speed. The larger diameter tire requires fewer revolutions per mile, so the speedometer will actually read lower at the same MPH.

I agree that could have been better; so thats been updated.

New Version is V91.

 

[Taz]

Muy bueno!

:beer:

 

[MrSwa]

I have something similar to this I put together. First question/comment, I thought the stock wheels were 26mm offset, not 29? Anyone shed any light on this?

Also, it is interesting to see your measurements for the hub to xx. I have collected some of this data on my car, and it was good to get some confirmation of the measurements I took (they were extremely rough when I did them). Did you take these measurements with the stock IRS bolts? Stock fender (not rolled)?

 

[Black Cobra]

I have something similar to this I put together. First question/comment, I thought the stock wheels were 26mm offset, not 29? Anyone shed any light on this?

Also, it is interesting to see your measurements for the hub to xx. I have collected some of this data on my car, and it was good to get some confirmation of the measurements I took (they were extremely rough when I did them). Did you take these measurements with the stock IRS bolts? Stock fender (not rolled)?

The Ford Racing part number is M-1007-S179 - Jegs and Summit still list this wheel as having a 6.12" backspace. I found a 2006 Ford racing catalog on google and it shows a 6.12" backspace as well. This equates to a 28.45mm offset or a 1.12" offset; if the wheels overall width is 10" exactly. Summit Racing shows it at 29mm. 29mm works with the 6.12 backspace if the wheel measures 9.96" overall.

Some of the after market 03 style wheels with a 26mm offset list a 6.02" backspace; which would be correct for a 10" overall wheel width.

I did my measuring with the tire still on the rim and sitting on the ground. My "C" measuremnet is the shortest one I got to the fenderwell and not the IRS bolt. I have a stock fender and IRS bolt. I'll have to take some more measurements next time I have the rear wheels off (few weeks). My hub to XX are all calculated based on the 6.12 backspace spec and the assumption the wheel is 10 inches exactly and the actual width of my rear tires.