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Randy's Ring & Pinion
Calculators

RPM
Enter Ratio, Tire Height, and Speed (mph) then click Solve to calculate RPM

Ratio Tire Height Speed  
Auto* AOD* Manual* 5 Speed*
* Auto = D in an AOD
* AOD is calculated at .70 transmission ratio
* manual = 4th in a 5 speed
* 5 speed is calculated at .80 transmission ratio


Transmission Ratio RPM
Enter R&P Ratio, Tire Height, Speed (mph), and Transmission Ratio, then click Solve to calculate RPM

R&P Ratio Tire Height Speed Trans Ratio
   
 
Recommended Towing RPM
4 cl 2200-3200
6 cl 2000-3000
Big Block 1600-2600
Small Block 1800-2800
Ford 6.0L 1900-2400
Ford Diesel (Non-Turbo) 1600-2500
Ford Diesel (Turbo) 1400-2200
Dodge Diesel 1400-2200
GM Diesel 6.2L 1800-2800
GM Duramax Diesel 1800-2400

Transmission Gear Ratio Chart
 
  1st 2nd 3rd 4th 5th 6th
Powerglide (sm. blk) 1.76 1.00        
Powerglide (big blk) 1.82 1.00        
Turbo 350 2.52 1.52 1.00      
Turbo 400 2.48 1.48 1.00      
Turbo 700R-4 3.06 1.63 1.00 0.70    
M20 (1963-65) 2.56 1.91 1.48 1.00    
M20 (1966-74) 2.52 1.88 1.46 1.00    
M21/M22 2.20 1.64 1.27 1.00    
Super T10 (S-code) 2.43 1.61 1.23 1.00    
Super T10 (W-code) 2.64 1.75 1.34 1.00    
Super T10 (P-code) 2.43 1.76 1.47 1.00    
Super T10 (U-code) 2.88 1.91 1.33 1.00    
Richmond 4+1 3.27 2.13 1.57 1.23 1.00  
Richmond 6-speed (a) 3.27 2.13 1.57 1.23 1.00 0.78
Richmond 6-speed (b) 3.01 1.88 1.46 1.19 1.00 0.62
Borg Warner T56 2.66 1.78 1.30 1.00 0.74 0.50
Borg Warner T56 3.36 2.07 1.35 1.00 0.84 0.62
Borg Warner T56 2.97 1.94 1.35 1.00 0.84 0.62
Borg Warner T56 2.97 2.07 1.43 1.00 0.80 0.62
ZF 6-speed 2.68 1.80 1.29 1.00 0.75 0.50
Toploader (close ratio) 2.32 1.69 1.29 1.00    
Toploader (wide ratio) 2.78 1.93 1.36 1.00    
Toploader (overdrive) 3.29 1.84 1.00 0.80    
200-4R 2.74 1.57 1.00 0.67    
4L60E 3.06 1.63 1.00 0.70    
4L80E 2.48 1.48 1.00 0.75    
Tremec 3550 3.27 1.98 1.34 1.00 0.68  
T-5 (F-body) V8, 83-87 2.95 1.94 1.34 1.00 0.74  
T-5 (F-body) V8, 88-92 2.95 1.94 1.34 1.00 0.73  
T-5 (F-body) 83-87 3.35 1.99 1.33 1.00 0.68  
T-5 (F-body) 88-92 3.97 2.34 1.46 1.00 0.79  
Saginaw 3 speed (all) 2.54 1.88 1.00      
Saginaw 4 speed (all) 2.20 1.64 1.47 1.00    


Tire Height
Enter Tire Width , Aspect and Wheel, then click "Solve" to calculate Tire Height.

Width Aspect Wheel
    
Street tires are rated using three numbers for example 225/70R15 or 255/70/15. In our example 225 is the Width in mm if the tire was measured from the bottom of bead to bottom of bead. In our example 70 is the Aspect, which means that the sidewall is 70% as tall as the tread is wide. In our example 15 is the the Wheel, the size of the wheel in inches, also called rim size. Placing the example numbers in the corresponding fields you will get a Tire Height of 27.4. Place your corresponding numbers into the fields below to calculate your tire height.