Going Back to Factory 30s w 3.07 Gearing?

BDiddy

BDiddy

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Joined
Jul 27, 2021
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33
Location
North Bend, WA
TLDR: My current 225/70r16 KO2s weigh 35lbs each. A 30x9.5x15 KO2 weighs 39lbs each. How much can I expect the 4lb different per tires to slow my Jeep down with 3.07 gear?

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Hey guys. My 2000 Sahara came with dealer added option 16” wheels and 225/70r16 Michelin LTX tires. I know this because the original spare was on it. It also has 3.07 gearing. I’m guessing these smaller Michelins, 16” wheels and 3.07 went well together. PO installed some mega huge load range E toyos and they were bald. I installed 225/70r16 KO2s in load range C about 2.5 years ago when I bought it in an attempt to go back to a smaller tire similar to what came on it.

I found a set of stock 15” wheels for sale near me and considering picking them up because it opens the door to so many more tire options. I’d like to get closer to the door jamb sticker meaning pick up some 15” wheels and 30x9.5x15 KO2s.

What I noticed is that my 225/70r16 KO2s weigh 35lbs each. A 30x9.5x15 KO2 weighs 39lbs each. How much can I expect the 4lb different per tires to slow my Jeep down with 3.07 gear? Safer to stick with the smaller tires?
 
The 225/70 R16 over diameter is 28.4” and the 30x9.5 R15 is a 29.5” tire.
The 4 lbs increase per tires tire and the increase in tire OD of 1.1” will drop the engine operating RPMs. Both of these will create a small loss in throttle response on the highway; due to a drop in engine RPMs and the slight addition of weight.
 
Last edited:
bmcgc said:
Was a 16" wheel an option on a Sahara? A 30-9.5-15 is 29.5" tall.
Click to expand...

Yes it was, and when optioned with the 16" alloy the tire spec was the 225/70R16 as indicated by the OP. Here's a pic of the wheels (stolen from this thread):

img_3186-jpg.21891


Here's a clip from a factory build sheet showing they're stock:
screenshot-2023-06-25-at-8-09-21-am-png.png


And a link to said build sheet.
 
Last edited:
BDiddy said:
What I noticed is that my 225/70r16 KO2s weigh 35lbs each. A 30x9.5x15 KO2 weighs 39lbs each. How much can I expect the 4lb different per tires to slow my Jeep down with 3.07 gear? Safer to stick with the smaller tires?
Click to expand...

You won't notice any significant difference, unless your butt-dyno is finely tuned. :unsure:
 
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A 1” difference won’t be very noticeable, although you are on the worst ratio to do that with. So it’ll be worse and more noticeable than if you had 4.10 or something.
 
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