Lets talk about 37s and 8th gear...

[inb4ammo]

My Tundra with 4.10 gears and 35s would shift out of 6th way too often even in the flattest parts of southern OK and north TX.

If you’ve got 37s (or even heavy 35s) with Rubicon 4.10 gears, have you been able to stay in 8th on the highway at 70+?

This may be the last question I need to answer before jumping on the Mopar lift and 37s train.

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[Skye]

I'll bump this post! Would love to know too.
Planning the Cooper STT Pros in a 35.

What can I expect with highway cruising?

 

[WXman]

My guess is absolutely not.

Granted, mine is a Sport with 3.45s but even with the 35 lb. flimsy stock tires, it'll shift down to 7 on any incline at 70 MPH. 4.10 gears ain't going to push 37s down the road in 8th gear. I don't see that happening. In fact, I don't see it staying in 7th much unless you live in Kansas.

 

[OnlyOne]

About half the time for me. I’m actually surprised how much time it spends in 8th. But I don’t ever really notice anymore, it shifts so smooth. As soon as I get a head wind it pretty much stays in 6th and 7th.

 

[Jkohler]

I can believe more people haven't chimed in on this that are running 37's. I'd like to run them but at this point I believe all have to do a gear change. After driving my rubicon for a little time now it seems like even with the 33's it doesn't take much to come out of 8th gear. Granted I live in the mountain area so there isn't much flat ground.

 

[OnlyOne]

I see zero reason to regear a Rubicon. I live in the mountains and it’s one peppy little bastard. Amazing the difference between my little 2dr JK and this JL. Even with 4 people and towing a trailer doesn’t bother it.

 

[boogie]

well that's a cool set up you have there!

 

[Arkewn]

I've seen multiple posts around that folks with 37"s have some trouble staying in 8th gear. 37"s *look* the best but there are so many added costs with jumping to 37"s (mpg, tail gait kit, potential re-gear, etc). The 35" tire options are not good with heavy tires and only E rated options. I wouldn't think it would be this hard to pick a freakin tire!?

 

[cliff538]

I see zero reason to regear a Rubicon. I live in the mountains and it’s one peppy little bastard. Amazing the difference between my little 2dr JK and this JL. Even with 4 people and towing a trailer doesn’t bother it.

OnlyOne, I'm struggling between 35's and 37's on my JLU. You seem to be totally happy going the 37" route... any regrets? wish you would of started with 35's?

I've purchased Cooper STT Pro 37" tires but they are not mounted yet, just curious on more detailed thoughts from you on your tire size choice.

Thank you in advance, Cheers!

 

[Mojito Mojo]

I've seen multiple posts around that folks with 37"s have some trouble staying in 8th gear. 37"s *look* the best but there are so many added costs with jumping to 37"s (mpg, tail gait kit, potential re-gear, etc). The 35" tire options are not good with heavy tires and only E rated options. I wouldn't think it would be this hard to pick a freakin tire!?

I’ve found 2 C rated options in a 35” x 17” tire:

BFG Ko2 315 x 70R x 17 C
Nitto Trail Grappler 35 x 11.5 x 17 C (this one is about 1 inch narrower tread width)

 

[inb4ammo]

The 35" tire options are not good with heavy tires and only E rated options. I wouldn't think it would be this hard to pick a freakin tire!?

The 315/70 BFG KO2 is a great alternative.

I'm avoiding M/Ts for now and I agree with you, this is too difficult to choose. I've ran Falken Wildpeak A/T3Ws and Ironman All Country M/Ts in 35s and loved the Falkens. I'm torn between Ridge Grapplers and Wildpeaks myself, but both are a heavy E rated tire.

 

[passingnotes]

I’ve found 2 C rated options in a 35” x 17” tire:

BFG Ko2 315 x 70R x 17 C
Nitto Trail Grappler 35 x 11.5 x 17 C (this one is about 1 inch narrower tread width)

i’m puttong on nitto ridge grapplers next week, 285/75, so about 34 inches in a C, looks like a happy medium, on a sport s and not planning to regear

 

[Mojito Mojo]

i’m puttong on nitto ridge grapplers next week, 285/75, so about 34 inches in a C, looks like a happy medium, on a sport s and not planning to regear

I would have ordered that tire too if I had gotten a Sport. I eventually order the Rubicon so I wanted to go up to 35”. You will still have to do a small lift won’t you?

 

[OnlyOne]

OnlyOne, I'm struggling between 35's and 37's on my JLU. You seem to be totally happy going the 37" route... any regrets? wish you would of started with 35's?

I've purchased Cooper STT Pro 37" tires but they are not mounted yet, just curious on more detailed thoughts from you on your tire size choice.

Thank you in advance, Cheers!

No regrets! You won’t either. Great choice on tires, and you’ll be surprised how little they affect your JL. Don’t even look back. There’s no way I would put anything smaller than 37’s on a JL Rubicon. Here’s a couple flex pics from tonight. No spacers and factory wheels.

 

[OnlyOne]

My guess is absolutely not.

Granted, mine is a Sport with 3.45s but even with the 35 lb. flimsy stock tires, it'll shift down to 7 on any incline at 70 MPH. 4.10 gears ain't going to push 37s down the road in 8th gear. I don't see that happening. In fact, I don't see it staying in 7th much unless you live in Kansas.

Actually with no headwind, here at 7000 ft it stays in 8th at 70 most of the time. You can tell a small difference in shifting but there is an enormous difference between 3.45s and 4.10s. As I said in an earlier post I am surprised how much it stays in 8th. I see no reason to regear for 37’s in a Rubicon. Obviously, with a JLUS it might be a good idea to regear but even then it’s probably tolerable.

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