Gears and wheel speed

With 11R24.5, you will be going fast enough to go to jail! Around 89 mph.

 

Google search "RPM calculator"

Just input tire height or tire circumference, engine RPM, transmission ratio and rear axle ratio and it will calculate your wheel speed. Or input your desired speed and it'll tell you your engine RPM.

 

Simple math equation for this.

Speed × gear ratio × rear end ratio × tire rev per mile / 60

Tire revs for common sizes

475=11R24.5
495=11R22.5 and 295/75R24.5
484=12R22.5 and 315/80R22.5
514=295/75R22.5, 275/80R22.5 and 445/50R22.5 (wide base singles)

Direct transmissions of course have a 1:1 top gear but overdrives can vary

Eaton 9/13/18 speeds have a .73 top gear (except the old RTO gear boxes which have a .87 top gear and the RTOO double overdrive which had a .62 top gear)

Eaton 10 speeds (and rockwell/meritor) have a .74 top gear ratio.

Eaton 15 speeds have a .79 top gear ratio.

Volvo I shifts (mack M drive) have a .78 tip gear ratio.

The old Eaton 5 and 7 speeds have .75 top gear ratios.

Allison automatics with 6 speeds had a .64 top gear ratio

Trying to remember the top ratios of the Spicer gearboxes.

 

Your formula is not phrased correctly, as we are trying to solve for speed.

This is the formula; speed (v) final drive ratio (t) rear end ratio (rt) revolutions per mile (rp)

So the formula is written
v=rpm/t/rt/rp*60, or v=2000/.75/475*60, or 86.4 mph.

I rough calculated that my truck turned about 1350 at 55 with 3.90s. At 2000 rpm, that is 88.89 mph. Not exact, but close.

 

Nerd.

 

You both are, but good info to know nonetheless...

 

I was thinking hammer down through a small town and let Barney Fife or Dirty Lyle clock you on the old speed gun!

I am sure Buford T. Justice could also give you a written copy of the top speed of the old Pete

 

/ means divide.
* means multiply.

The way you have your formula written says to take the total engine RPM, divide that by .75, then divide that result by 475, then multiply that result by 60.

Remember your order of operations - PEMDAS. From left to right, parenthesis and exponents first, then multiplication & division, then addition and subtraction.

 

There's that new math being posted again.