Our Calculators!

(THESE ARE JUST ESTIMATES BASED ON SIMPLE CALCULATIONS!)

Calculate HP from Trap Speed

Vehicle weight in pounds (including driver)
lbs

Trap speed at end of 1/4 mi in m.p.h.
m.p.h.


You are making : HP at the rear wheels and HP at the flywheel*.
JavaScript must be enabled in your browser for the calculation to work.

*Note:  Assuming a 18% drive train loss.

Calculate HP from ET

Vehicle weight in pounds (including driver)
lbs

ET in seconds
sec


You are making : HP at the rear wheels and HP at the flywheel*.
JavaScript must be enabled in your browser for the calculation to work.

*Note:  Assuming a 18% drive train loss.

Calculate Tire Diameter
Tire width - Series - Wheel Diameter
Example 275 - 60 R 15
Tire Width
 Tire Series
 Wheel Diameter


Tire diameter in inches
JavaScript must be enabled in your browser for the calculation to work.

 

Calculate mph for RPM range
Tire diameter
 Gear Ratio

This calculation assumes the car's transmission is in drive or 1:1 ratio, no overdrive. For Overdrive mutliply the overdrive ratio times the rear and gear ratio. Example a 5R110 transmission has an overdive ratio 0.7:1. For a 4.11 rear end multiply 4.11 x 0.7 = 2.877. Enter 2.877 as the number for the gear ratio to calculate speeds in overdive.
JavaScript must be enabled in your browser for the calculation to work.
1000 rpm mph 3000 rpm mph
1500 rpm mph 3500 rpm mph
2000 rpm mph 4000 rpm mph
2500 rpm mph 4500 rpm mph

 

Calculate Rear End Gear Ratio
Enter the tire diameter in inches, rpm's of the motor at a certain speed as indicated by your speedometer in mph. This calculation assumes the car's transmission is in drive or 1:1 ratio, no overdrive.
Tire Diameter (in)
 RPM
 Speed at RPM (mph)


Rear End Gear Ratio
JavaScript must be enabled in your browser for the calculation to work.

 


Quick Tire Size Converter
P-Metric Style

Example: 215/75R15
/ R
Copy values to:

Inch Style

Example: 31 x 10.50 x 15
x x

 
Different Tire Comparision
Tire A:

Tire B:

Just calculate Tire A's dimensions
Compare Tire A to Tire B
Calculate tires equivalent to Tire A (Use Tire B fields to narrow search). Max height difference: inch(es).

Fill in the following if you're interested in calculating gearing and/or RPM changes

Rearend ratio:     RPM:
 
Tire A: / R

Tire B: / R

Just calculate Tire A's dimensions
Compare Tire A to Tire B
Calculate tires equivalent to Tire A (Use Tire B fields to narrow search). Max height difference: inches.

Fill in the following if you're interested in calculating gearing and/or RPM changes

Rearend ratio:     RPM:
 

Note: The Javascript "quick calculator" at the top of the page is based on code from http://www.4lo.com, written by Mark I. Medina.

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