Tire and Gear calculator
#1
Tire and Gear calculator
I found this interesting equation about how to get your truck running like it was designed to after you change tire/wheel sizes.
First determine your wheel diameter of your new and old tires.
If you don't feel like measuring or are unsure check out this site.
http://www.net-comber.com/tirecalc.html
My example:
Old tire size 235/75-16 = 29.88 inches
New tire size 275/55-20 = 31.91
Gear Ratio = 3.42
Step 1 [Old Tire Size]/[New Tire Size]*[Current Gear Ratio] = [New Gear Ratio]
29.88/31.91*3.42 = 3.20
So switching to 20's actually makes my 3.42 act like 3.20 (this sucks!!)
Step 2 [New Tire Size]/[Old Tire Size]*[Gear Ratio] = [New Gear Ratio]
31.91/29.88*3.42 = 3.65
So to get my truck back to factory optimized parameters I need to increase my gears to at leat 3.65 (3.73) to get to back to decent gas mileage.
I hope everyone enjoys this......
First determine your wheel diameter of your new and old tires.
If you don't feel like measuring or are unsure check out this site.
http://www.net-comber.com/tirecalc.html
My example:
Old tire size 235/75-16 = 29.88 inches
New tire size 275/55-20 = 31.91
Gear Ratio = 3.42
Step 1 [Old Tire Size]/[New Tire Size]*[Current Gear Ratio] = [New Gear Ratio]
29.88/31.91*3.42 = 3.20
So switching to 20's actually makes my 3.42 act like 3.20 (this sucks!!)
Step 2 [New Tire Size]/[Old Tire Size]*[Gear Ratio] = [New Gear Ratio]
31.91/29.88*3.42 = 3.65
So to get my truck back to factory optimized parameters I need to increase my gears to at leat 3.65 (3.73) to get to back to decent gas mileage.
I hope everyone enjoys this......
#2
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Yup, that's it! Effective gear ratio. That's really what matters. I constanly see people decide or debate which gear ratio is better without any regard to tire size. Because a 4.10 is too much in your buddy's f-body doesn't mean its too much in your truck.
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