Differential ratio change

Reply Subscribe

Thread Tools

Search this Thread

Jan 23, 2008 | 10:56 AM

40searay

Thread Starter

Junior User

Joined: Sep 2004

Posts: 84

Likes: 0

From: Palm Harbor Florida

Differential ratio change

Does anyone have a site that calculates the new gear ratio when changing tires? I saw it recently and I've looked all over and can't find it again (of course). I just changed from 295's to 315's and want to know what my new gearing is. I think it's around 3.55

Jan 23, 2008 | 11:46 AM

jimmy-six

Laughing Gas

Joined: Mar 2004

Posts: 1,019

Likes: 6

From: Fountain Valley

I use a program called GearCalc with my Land Speed cars. It works with final ratios, tire diameter, and trans ratios, and RPM. Good luck

Jan 23, 2008 | 04:11 PM

BobsF350

Elder User

Joined: Apr 2004

Posts: 614

Likes: 0

Tires dont change your gear ratio
it is what it is

Jan 23, 2008 | 06:30 PM

wrangler76

Senior User

Joined: Dec 2000

Posts: 296

Likes: 0

From: Carson USA

Your "gear ratio" describes your ring and pinion gear choice... When discussing tire size we usually are talking about "revolutions per mile" or changes in indicated speed vs true speed on the speedometer. Hope this helps!

Jan 24, 2008 | 09:22 AM

edjunior

Cargo Master

Joined: Jan 2007

Posts: 2,243

Likes: 79

From: Roman Forest, TX

I think searay's looking for "effective" gear ratio, not actual gear ratio. Anyway, is this what you're looking for?

https://www.ford-trucks.com/calculat.../p-tire_sizes/