Tire size recommendation

[Wabujitsu]

FWIW, I had a Sport JLU previously, with 35x12.50 MTs, 2.0T and 8 speed. I noticed only a very slight difference between those and the 285/70R17s I had previously.

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[Megawatt]

……
Or should I move up to a set of 315/70r17 or 35x11.50r17s? ….

I just when to bigger tires last night. I originally was set on 35x11.5” -17. I wanted 10lbs less weight. One inch narrower for more clearance to reduce the poke. Nitto list 35x 11.5” recon grapplers that were $80 less each tire compared to the same model at 35x12.5”.

Short story on why I now have 35x12.5” tires….
Look on discount tire and there are only two tires available in 35x11.5” from all manufacturers. After two weeks of having the order cancelled by Nitto we were told they are in warehouse but not release to public yet for some reason. No ETA on when.

If you need a replacement in the future it could be a long time before you get a 11.5” tire because it’s not common.

I stopped being concerned about tire weight and more about load rating and number of sidewall plys. You’re going to feel bigger load rating long before a 10 lb heavier tire in terms of comfort.

 

[XX4XEXX]

I second this. 285s are fine for maximum flex and droop.

Nice looking build! If you're more into looks go with the bigger tires- in FL you shouldn't have any problems with gearing. If it were me I'd stay with your 285/75/17s but I prefer function over form so take my advice with a grain of salt. My next set will be 285/75/17 E Trail Grapps for better traction in the mud.

 

[grimmjeeper]

At least with Ruby 4:10 gears and AT, not necessary for up to 40's.

I've got 2.5" lift and 38's.

This is really bad advice no matter how often you post it.

The automatic transmission masks the inadequacy of tall (lower number) gears. Just because you happen to be able to get by with it doesn't mean it's a good combination. You can't give good advice based only on the anecdotes of your own personal experience.

Simply put, 3.6 needs more gear. 4.10s are only barely adequate for 35s. You're better off with 4.56s or 4.88s. As far as bigger tires, they need shorter gears. I wouldn't do 40s with anything less than 5.38s if I had the 3.6.

 

[J0E]

This is really bad advice no matter how often you post it.

The automatic transmission masks the inadequacy of tall (lower number) gears. Just because you happen to be able to get by with it doesn't mean it's a good combination. You can't give good advice based only on the anecdotes of your own personal experience.

Simply put, 3.6 needs more gear. 4.10s are only barely adequate for 35s. You're better off with 4.56s or 4.88s. As far as bigger tires, they need shorter gears. I wouldn't do 40s with anything less than 5.38s if I had the 3.6.

Just because you believe in the much cited myth you must regear like most doesn't make it true. My transmission temperate never gets hot. I posted a couple other folks with this combo. The 2.0 T does work better than the 3.6, I'll agree with that.

4.10s are only barely adequate for 35s.

Why don't you take a look at my bt39.com/GearWheelSpeed for factual comparisons. According to you, a non-Rubicon shouldn't even work with factory gears and tires.

My rig is optimized for off road, not light to light races. If I want to drag race, I'll use a factory 8 second Plaid.

4.10s are only barely adequate for 35s.

Barely adequate for what besides light to light racing?

I wouldn't do 40s with anything less than 5.38s if I had the 3.6.
You must not wheel hard and are optimizing for the highway. That 5.38 would shear the first time you crawled a hard line.

 

[grimmjeeper]

Just because you believe in the much cited myth you must regear like most doesn't make it true.

One question. How many assertions does it take to make a fact? ?

I'll take good engineering over your anecdotes any day of the week

 

[azwjowner]

Just because you believe in the much cited myth you must regear like most doesn't make it true. My transmission temperate never gets hot. I posted a couple other folks with this combo. The 2.0 T does work better than the 3.6, I'll agree with that.

4.10s are only barely adequate for 35s.

Why don't you take a look at my bt39.com/GearWheelSpeed for factual comparisons. According to you, a non-Rubicon shouldn't even work with factory gears and tires.

My rig is optimized for off road, not light to light races. If I want to drag race, I'll use a factory 8 second Plaid.

4.10s are only barely adequate for 35s.

Barely adequate for what besides light to light racing?

I wouldn't do 40s with anything less than 5.38s if I had the 3.6.
You must not wheel hard and are optimizing for the highway. That 5.38 would shear the first time you crawled a hard line.

Regardless of whether the transmission ratios can accomodate larger tires, I've never been comfortable with the fact that larger tires without regearing are putting increased torque stress on the transmission components 100% of the time. I don't know how much extra margin, if any, is baked into the transmission, but either you're losing that margin or you're shortening the lifespan of the transmission.

 

[c20040215]

This is really bad advice no matter how often you post it.

The automatic transmission masks the inadequacy of tall (lower number) gears. Just because you happen to be able to get by with it doesn't mean it's a good combination. You can't give good advice based only on the anecdotes of your own personal experience.

Simply put, 3.6 needs more gear. 4.10s are only barely adequate for 35s. You're better off with 4.56s or 4.88s. As far as bigger tires, they need shorter gears. I wouldn't do 40s with anything less than 5.38s if I had the 3.6.

It's an open forum. There will be a lot of opinions not a lot of facts. Best way to react is to not react. Or you would never see the end of it.

It's leverage and simple math.

 

[J0E]

One question. How many assertions does it take to make a fact? ?

I'll take good engineering over your anecdotes any day of the week

But you haven't provided any good engineering.

It's an open forum. There will be a lot of opinions not a lot of facts. Best way to react is to not react. Or you would never see the end of it.

It's leverage and simple math.

It is simple math, done on my bt39.com/GearWheelSpeed?
A JLR with stock gears and 37's is geared almost identical to a JLS with 31.5" tires in high range. I don't care about hi range, my JLR is a dedicated crawler. But in low range a JLR on 37's is geared lower than the JLS.

Just delete the Model's your not interested in.

 

[grimmjeeper]

It is simple math, done on my bt39.com/GearWheelSpeed?
A JLR with stock gears and 37's is geared almost identical to a JLS with 31.5" tires in high range.

All you're proving is that a JLR with stock gears on 37s is just as under geared as a JLS is on stock tires. So putting 37s on a Rubicon without regearing nullifies all of the gearing advantages that a Rubicon comes with from the factory.

You may be able to make that work on the trails you run but you're still under geared. You are just too obtuse to see it. Sorry.

 

[J0E]

All you're proving is that a JLR with stock gears on 37s is just as under geared as a JLS is on stock tires. So putting 37s on a Rubicon without regearing nullifies all of the gearing advantages that a Rubicon comes with from the factory.

You may be able to make that work on the trails you run but you're still under geared. You are just too obtuse to see it. Sorry.

So going vertical isn't good enough for you? How about 36 degrees pitch?

LOL, climbs vertical in M2, AT never gets hot (I do M1). I'm not going to try to convince you as several of us know what works are aren't driven by interstate optimization driving.

Come follow me sometime and you can see for yourself.

 

[grimmjeeper]

So going vertical isn't good enough for you? How about 36 degrees pitch?

LOL, climbs vertical in M2, AT never gets hot (I do M1). I'm not going to try to convince you as several of us know what works are aren't driven by interstate optimization driving.

Come follow me sometime and you can see for yourself.

Still throwing pointless anecdotes at me with a side of ad homenim?

Yeah. We're done here.

 

[2nd 392]

Instead of spending ~$2K for an extra virtually unnoticeable 1/2” of tire as @Mudduck stated, spend it more wisely for gears. Get tires when needed— so no extra cost. ?

 

[J0E]

Instead of spending ~$2K for an extra virtually unnoticeable 1/2” of tire as @Mudduck stated, spend it more wisely for gears. Get tires when needed— so no extra cost. ?

1/2" is hardly unnoticeable, at least the way we wheel. But it's more like 3/4". And it's not just height. I'm going from very short 37x12.5R17 KM3's to 38x13.5R17 Nitto's which are about 1.5" wider. I've also got bead locks for the Nitto's. Dropping the front from 13 PSI to 9PSI and rears from 10 PSI to 7 PSI, I'll see a non-trivial traction and clearance improvement - I'd I won't debead the fronts so often in the rocks.

Now gear changes are totally unnoticeable when wheeling with the 4:1 xfer case, AT, and 2.0 turbo.

As I said, when I sell the JLR next year for my build on tons, I won't get a penny extra for regears. I won't get a penny extra for 38's over 37's, but at least I'll enjoy them. 98% chance a mall crawler will buy my rig.

I did a fairly accurate measurement here of my 37x12.5 KM3s at 35 PSI and came up with 35 13/16".

 

[2nd 392]

1/2" is hardly unnoticeable, at least the way we wheel. But it's more like 3/4". And it's not just height. I'm going from very short 37x12.5R17 KM3's to 38x13.5R17 Nitto's which are about 1.5" wider. I've also got bead locks for the Nitto's. Dropping the front from 13 PSI to 9PSI and rears from 10 PSI to 7 PSI, I'll see a non-trivial traction and clearance improvement - I'd I won't debead the fronts so often in the rocks.

Now gear changes are totally unnoticeable when wheeling with the 4:1 xfer case, AT, and 2.0 turbo.

As I said, when I sell the JLR next year for my build on tons, I won't get a penny extra for regears. I won't get a penny extra for 38's over 37's, but at least I'll enjoy them. 98% chance a mall crawler will buy my rig.

I did a fairly accurate measurement here of my 37x12.5 KM3s at 35 PSI and came up with 35 13/16".

Typical 33.8-.9 to 34.4-.5 is ~1/2” not 3/4”. Yes they are more narrow, but Paid For and a good tire— use them up. He does Not have a 4-1 TC in a Willys, He does Not only drive off road In low range even if he did have 4-1. He does not have a 2.0T………..Upon replacing 32.8” KO2’s with 34.5” AT3’s I lost a half step in road performance even with a V8, and low hwy rpm below ~70mph. Replaced 3.73’s with 4.56’s, gained a full step with good hwy rpm. Considered 4.10’s, would have been OK, delighted with 4.56’s.

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