I'm sure this subject has been hammered to death. But there are a number of calculators online that simply suck. Attached is the spreadsheet I created for calculating engine RPM given tire size, axle ratio, transfer case ratio (so you know our crawl), at each speed in 5mph increments.
It's currently set to calculate for an SM465 and NP241C.
If you want to edit this, all your inputs are in Bold Italic Red. Change these for whatever transmission, transfer case, tire size, and axle ratio you want to calculate. Use the Actual Tire Height listed in Summit Racing if you want perfect calculations (a 35x12.50x15 is not 35" tall).
Hope it helps someone. Given, this works great for manual transmissions, I have no idea how the torque converter affects these calculations (I suppose this shows the lowest they could possibly be?).
https://drive.google.com/open?id=0BwBk9CVQ48n-NERIY2w3N212dnM
It's currently set to calculate for an SM465 and NP241C.
If you want to edit this, all your inputs are in Bold Italic Red. Change these for whatever transmission, transfer case, tire size, and axle ratio you want to calculate. Use the Actual Tire Height listed in Summit Racing if you want perfect calculations (a 35x12.50x15 is not 35" tall).
Hope it helps someone. Given, this works great for manual transmissions, I have no idea how the torque converter affects these calculations (I suppose this shows the lowest they could possibly be?).
https://drive.google.com/open?id=0BwBk9CVQ48n-NERIY2w3N212dnM
