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Matt, Engineer
Category: Motorcycle
Satisfied Customers: 21973
Experience:  Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
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HD10 defender I have 30" tires on it ground clearance.

Customer Question

HD10 defender I have 30" tires on it for the ground clearance. Wondering what I can do to pick up the hp that I lost from bigger tires. Are if you guys have gear sets for that.
Submitted: 1 year ago.
Category: Motorcycle
Expert:  Matt replied 1 year ago.


you have 2 routes

either lower the rear axle gear ratio

or tune the engine up or fit something more powerfule

by far the easiest method is to reduce the rear axle ratio

The diff will most likely only be either 4.7:1 Series diff or a standard 3.54:1 and you should be able to tell the difference between them using the propshaft revolutions as 10 wheel revs will either produce 35 or 47 prop revs.

Counting the pinion and crownwheel teeth is of course the "correct" way but unless you have a "special" there are only two factory diff ratios and the vast majority of diffs out there will be the 3.54:1 which is what has been fitted in all 90/110/Defender, RR and Discovery vehicles.

Customer: replied 1 year ago.
You obviously have no clue what the hell I'm talking about. It sure the hell isn't a damn range rover are a suv period!!! Give me a break ok ready for my refund!!!!Now!!
Expert:  Matt replied 1 year ago.

my apologies

I saw the 'defender' title and assumed it was a land rover

I'll opt out so another expert can help

good luck

Customer: replied 1 year ago.
No I'm done refund nnow please!!!
Expert:  Matt replied 1 year ago.


you have to request the refund yourself