Pro UTV Parts

Pro UTV Parts Pro UTV Parts Owner, Craig Stumph has 57 years Off-Roading experience and specializes in parts to enhance your Off-Roading experience while looking good.

Memorial day sale on Elektric Offroad Design products. Great sale. Shop now.
04/17/2026

Memorial day sale on Elektric Offroad Design products. Great sale. Shop now.

Gear/Tire Changes vs Speed Calculations Made SimpleTrue GPS speed decreases proportional to the % reduction in gearing. ...
12/03/2025

Gear/Tire Changes vs Speed Calculations Made Simple

True GPS speed decreases proportional to the % reduction in gearing. This applies to transmission and portal gear lift/reductions. GPS true speed also increases proportional to tire size increase. Speed decreases with tire size reductions.

In the example below we will not talk about reverse because it closely mirrors low range reduction.

Example:

Polaris Turbo with 30" tires moves up to 35" tires. (1- (30/25)) x 100 = 14.29% tire size increase.

Same Polaris Turbo lowers transmission gearing by 21% in low range and 32% in high range. High and low gear changes are additive to low range Polaris turbo transmissions. High range gear swaps apply to high range only and high is unaffected by low range gear changes.

Total Low Range Reduction = 21% + 32% = 53%

Top Speed Stock 30" tires (TSS) = 80 mph

Total Low Range Reduction (TLRR) = 53%
Low Range Reduction (LRG) = 21%
High Range Reduction (HRG) = 32%
Tire Size Increase (TSI) = 14.29%
New Top Speed (NTS)

(1- (HRG - TSI/100)) x TSS = NTS
(1 - (32%-14.29%/100)) x 80 mph = NTS = 65.83mph



Note: If you want your speedometer to read correctly see below.

https://www.proutvparts.com/products/polaris-speeddoctor-speedometer-correction-kit?_pos=1&_sid=912457ff3&_ss=r

https://www.proutvparts.com/products/super-atv-honda-speeddoctor-speedometer-correction-kit?_pos=2&_sid=912457ff3&_ss=r

https://www.proutvparts.com/products/super-atv-can-am-speeddoctor-speedometer-correction-kit?_pos=3&_sid=912457ff3&_ss=r

Pro UTV Parts has Several Halo 30s in stock at 17% off. Purchase now while this great deal is running.
11/02/2025

Pro UTV Parts has Several Halo 30s in stock at 17% off. Purchase now while this great deal is running.

SKU: H-HALO-30 33 Spline Halo 30 Diff for CanAm This is the best of the best, the Halo 30 locker setup is the strongest locker available anywhere for the Can-Am. Included is a billet case, 6 gear chromoly carrier, Halo locker kit, new seals and bearings, larger and stronger custom spider gears. The....

RIP Walker Evans
08/08/2025

RIP Walker Evans

Address

Delta, UT
84624

Opening Hours

Monday 9am - 5pm
Tuesday 9am - 5pm
Wednesday 9am - 5pm
Thursday 9am - 5pm
Friday 9am - 5pm
Saturday 9am - 1pm

Telephone

(801) 367-1395

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