Tire Advice

[HPD2000]

I am looking to buy a 2006 TJ Rubicon. It currently has 315/75/16 tires and a 4.5" lift. It tachs 2800-2900 rpms at 60 mph with a 4.11 rear differential. What size tire does this Jeep need to bring it into an acceptable rpm range?

 

[TerryMason]

I'm not up on Rubicons - is 4.11 the factory gearing, or did you regear it?

Manual or automatic?

I've got a 2005 TJ - 3.73, automatic, and 33x12.5 tires. It is fine, but I don't think I could go any larger without regearing.

 

[Jeepergeo]

Back into your answer from this table or one like it.

https://images.app.goo.gl/qa9QdGePh8mCvtWWA

Your gearing and tire size sounds like it is delivering an RPM that sounds about right to me for general around town and off road use, but not for a lot of highway driving.

Here is a site for converting tire sizes to inches.

https://www.crawlpedia.com/tire_size_converter.htm

 

[JPNinPA]

Using Jeepergeo links, which are good, you should have favorable low RPM at highway speeds with 35" tires on 4:11 gears. And those numbers seem correct.

What range rpm are you desiring?

I'll have to run some basic calculations to verify


Regards,
JPNinPA

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[JPNinPA]

So if you have an automatic in 3rd at 2850 rpm you would be doing 72mph if I calculated correctly. You might not have a corrected speedo /odometer from factory. So 31" tires will have you at 65mph at 2850rpm in 3rd gear.

Alternative is regearing to 4:56 or 4:88
Regards,
JPNinPA

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