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I have a dumb question

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Old 08-12-2010, 04:34 PM
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Default I have a dumb question

I'm looking at the gear ratio chart that is posted in several threads. Tire Size?

That is the actual (measured) tire size and not what is marked on the tire?
Old 08-12-2010, 04:40 PM
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Originally Posted by ECHO
What size tires are you looking at getting.. what JK Model do you have .. Auto or Manual?
I have 2010 JK 4 dr, automatic. 315 70R17 Tires (actual height = 33.75 inches)
Old 08-12-2010, 04:45 PM
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Originally Posted by ECHO
Which brand of tire and model
Kelly Safari TSR
Old 08-12-2010, 04:47 PM
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Use the actual measured diameter of the tire (with correct air pressure) to get the most accurate calculations.
Old 08-12-2010, 04:55 PM
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Originally Posted by ECHO
Was looking for the weight of each tire at a guess your looking at about 65lbs per.. since they are 34's.. what gear's do you have now?? do you have a tow package?
I have the tow package and 3.73 gears. I trying to decide between 4.88's or 5.13. I know most people on the forum say 5.13's for 35's. By looking at the chart and using the actual tire size, it says I would want to stay with 4.88's for overall drivability with full time O/D use.
Old 08-12-2010, 05:05 PM
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Originally Posted by ECHO
Guess I should have read your profile... with 3:73's you run about 2200 RPM at 60 - if you went up to 4:88's you RPM at 2700 at 60 and keep your performance.. but; between the weight of the tires.. The increased drag by raising the jeep alittle (tire hieght) it will affect MPG.. guess you need to decide which you really want to keep..

Allot of guy are running 3:73's with 33's, 34's and 35's without regearing..

I am running a two door, 6-spd - 33's w/ 3:21's... will regear someday.. I get by just fine right now
Actually at 60 mph in O/D im running about 1800-1900 rpm. I know I'm going to lose some MPG, just trying to keep a reasonable balance between performance and Mpg.
Old 08-12-2010, 05:06 PM
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I'm running 5.13's with 35" tires and really happy with the set up. As far as running 2200 rpm at 60, I'm running 2400 rpm at 70 mph. I would go with 5.13's if I was you but thats my opinion.
Good luck with the choice. BTW I get 16 1/2 mpg if I take it easy on the skinny pedal.
Old 08-12-2010, 05:09 PM
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Originally Posted by jeepoholic
I'm running 5.13's with 35" tires and really happy with the set up. As far as running 2200 rpm at 60, I'm running 2400 rpm at 70 mph. I would go with 5.13's if I was you but thats my opinion.
Good luck with the choice. BTW I get 16 1/2 mpg if I take it easy on the skinny pedal.
Yes, I think I'm leaning towards the 5.13's. I was just looking at the chart and its kinda right in the middle.
Old 08-12-2010, 05:14 PM
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Thanks for the help!!
Old 08-12-2010, 05:35 PM
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You have an auto, you want the 5.13's. Browse the other 1000 gearing threads asking the same question for plenty of feedback.


Look at the number of people with 4.88's installed, that are saying they should have gone 5.13 (or 5.38 in the case of rubi owners)

Then compare that to the number of people with 5.13/5.38 that wish they had gone 4.88.

You will find quite a large number in the first group, and very very few in the latter. You will also see that, in general, 5.13/5.38 will get a bit better mpg's due to holding speed better (less dropping out of OD)


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