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Going to 315/70/17 tires on Willys JLU without "major" suspension modifications?

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Willys_Wonka

Willys_Wonka

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Good morning, Mike!

At about 28 psi cold, 30-31 hot, the ride is perfect! I was skeptical of LR E too, but now I’m a fan. Presumably, with lower PSI, it allows the sidewalls to “work” - to flex and help absorb bumps, etc, on and off-road. By the way, I don’t air-down when we go off-road, even on extremely challenging trails.

I and my wife are quite comfortable, and we are both disabled, with spine and other issues.
Jeff, you swayed my decision on tire size by introducing 35x11.5x17 this morning! I was certain 285/75/17 was my limit on 7.5 wheels while staying within the fender flares. Game changer on these 11.5's especially in a load range C. I'm running 285/70 so jumping to a 35, adding a set of .75-1" coil spacers should do the trick. Since the 35x 11.5 tires are basically 285 width and I have no existing rubbing, I shouldn't need to adjust the steering stops with these 35" tires at 11.5. I already have a R/C spare relocation bracket installed, so that's just waiting for the larger tire.
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Wabujitsu

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Jeff, you swayed my decision on tire size by introducing 35x11.5x17 this morning! I was certain 285/75/17 was my limit on 7.5 wheels and while staying within the fender flares, game changer on these 11.5's especially in a load rang C. I'm running 285/70 so jumping to a 35 a set of .75-1" coil spacers should do the trick. Since the 35x 11.5 tires are basically 285 width and I have no existing rubbing, I shouldn't need to adjust the steering stops on the 35" tires at 11.5. I already have a R/C spare relocation bracket installed, so that's just waiting the larger tire.
Awesome, Mike! Let me know how you like your new tires, after installation!
 

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I have owned several Wranglers with tires that measured 255/70R17, 255/70R18, 275/70R18, 34x10.5R17, 315/70R17 and 35x12.5R17.

Jeeps on 35s are total beasts on the trails on 35s, and look great.

But in my experience, these vehicles are happiest with tires that measure 32-34 inches tall and 10-11.5 inches wide. The added weight and size of 35x12.5 tires make these vehicles feel lumbering, the steering slow to respond, the ride more susceptible to potholes and ruts, and will kill your MPG.

The biggest limitation going to 35s will be your stock 3.45 gearing. While the 8-speed automatic will do an excellent job masking the problem, it will perform like a dog. Expect your fuel consumption to be 13-15 MPG. Those claiming to be getting 20+ MPG on 35s are full of shit.

All in all, 285/75R17 would be a perfect compromise between looks and performance. Those tires measure 34x11.2 inches.

Good luck.
 
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I have owned several Wranglers with tires that measured 255/70R17, 255/70R18, 275/70R18, 34x10.5R17, 315/70R17 and 35x12.5R17.

Jeeps are a total beast on the trails on 35s, and they look great.

But in my experience, these vehicles are happiest with tires that measure 32-34 inches tall and 10-11.5 inches wide. The added weight and size of 35x12.5 tires make these vehicles feel lumbering, the steering slow to respond, the ride more susceptible to potholes and ruts, and will kill your MPG.

The biggest limitation going to 35s will be your stock 3.45 gearing. While the 8-speed automatic will do an excellent job masking the problem, it will perform like a dog.

Expect your fuel consumption to be 13-15 MPG. Those claiming to be getting 20+ MPG on 35s are full of shit.

All said, 285/75R17 would be a perfect compromise between looks and performance. Those tires measure 34x11.2 inches.

Good luck.
Thanks, even with 11.5 instead of 12.5? Reduced mpg is expected going bigger, but low tens is close to a 30% reduction. It’s not a deal breaker regardless since I’m only clicking about 8k miles per year. I can always regear in a few years.
 

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Thanks, even with 11.5 instead of 12.5? Reduced mpg is expected going bigger, but low tens is close to a 30% reduction. It’s not a deal breaker regardless since I’m only clicking about 8k miles per year. I can always regear in a few years.
I say 11.2 inches because that’s the equivalent of 285mm wide. 11.5 inches should be fine. Wider tires add weight, contact patch, and start to go against the factory wheel width and offset.
 

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Thanks, even with 11.5 instead of 12.5? Reduced mpg is expected going bigger, but low tens is close to a 30% reduction. It’s not a deal breaker regardless since I’m only clicking about 8k miles per year. I can always regear in a few years.
The Mickey Thompson Baja Boss A/T comes in the best size of all, 255/85R17 (35x10x17).
 

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There is other tires with less width out there, you just have to do some work to find them.

Kenda Klever R/T 35x10.5x17 on stock wheels. Load Range D. As aldo98229 stated, a lot to consider besides tires rubbing. When you go 35", you are introducing a lot more issues that needs to be addressed.

KevinC

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There is other tires with less width out there, you just have to do some work to find them.

Kenda Klever R/T 35x10.5x17 on stock wheels. Load Range D. As aldo98229 stated, a lot to consider besides tires rubbing. When you go 35", you are introducing a lot more issues that needs to be addressed.

KevinC

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The goal is highest and widest but at the same time safety. It seems 11.5 or 285 is a sweet spot on the 17x7.5 wheel. I got 285 now, so definitely don’t want smaller.
 

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I have owned several Wranglers with tires that measured 255/70R17, 255/70R18, 275/70R18, 34x10.5R17, 315/70R17 and 35x12.5R17.

Jeeps on 35s are total beasts on the trails on 35s, and look great.

But in my experience, these vehicles are happiest with tires that measure 32-34 inches tall and 10-11.5 inches wide. The added weight and size of 35x12.5 tires make these vehicles feel lumbering, the steering slow to respond, the ride more susceptible to potholes and ruts, and will kill your MPG.

The biggest limitation going to 35s will be your stock 3.45 gearing. While the 8-speed automatic will do an excellent job masking the problem, it will perform like a dog. Expect your fuel consumption to be 13-15 MPG. Those claiming to be getting 20+ MPG on 35s are full of shit.

All in all, 285/75R17 would be a perfect compromise between looks and performance. Those tires measure 34x11.2 inches.

Good luck.
Aldo, depending on wind speed and direction, when I run into town and back for errands on my 35x12.50s (about a 30-35 mile round trip, no highway miles, mostly country at 55-65 MPH, and only a few city miles) I average between 18-21 MPG. I make this trip, on average, four times per week.

I will get 20+ MPG on the days when there is little to no wind. As you know, I have a built JLUR - but it does have the 2.0T. I guess that makes me “full of shit,” brother? 🤣
 

Rubi II

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Good morning, Mike!

At about 28 psi cold, 30-31 hot, the ride is perfect! I was skeptical of LR E too, but now I’m a fan. Presumably, with lower PSI, it allows the sidewalls to “work” - to flex and help absorb bumps, etc, on and off-road. By the way, I don’t air-down when we go off-road, even on extremely challenging trails.

I and my wife are quite comfortable, and we are both disabled, with spine and other issues.
Thank you for the reply Jeff, appreciate it! That's good information to know.
 

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Rubi II

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Mike, I forgot to add this: MTs are always going to be louder than less aggressive treads. However, I find the Falken Wildpeak MTs to be surprisingly quiet, but that WILL change over time. They will become louder as the tread wears down.
Yeah, I noticed that with my 285 M/T's. Were quiet when new and now with about 37,000 miles I'm hearing more but still not bad. Thanks for the info!
 

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Another thing is in PA, tire poke is not permitted. I need to stay within the fender flares or add extensions.
I think that mostly depends on who is inspecting your vehicle and whether or not the LEO is going to pull you over for it. I've been running the 315/70R17 KO2s for over two years and my garage has inspected it and doesn't bat an eye. He told me that if he has to measure it, then it's not going to pass. I've measured the tire poke on my Jeep with those KO2s and it's about 1.5 inches to the edge of the tread from fender lip.
 
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I can’t say you will or won’t have rubbing, so I won’t speak to that. On my previous Sport JLU with a 3.5” lift I had no problem with 35s, even with sway bar disconnected and at full flex.

You may find some shops won’t install those tires on a 7.5” rim, but generally off-road shops will do it with no problem. Make sure you drop the PSI enough that the edges of your tires have sufficient contact with the road; the narrower rim will cause the center of the tread to bulge at recommended pressures. I run mine at 28 PSI cold, 30-31 hot, and I’m getting even wear (Falken Wildpeak 35x12.50 MTs, load range E). Many well-intentioned folks will tell you it’s a safety hazard to run oversized tires on narrow rims, but the only danger is uneven tread wear and thus shortened tread life of the tires.
Not to get off the rails on discussion, but I just picked these up for 200 bucks! They should help entry for my short second half once the 35” are on. Ace Engineered rail steps.

Jeep Wrangler JL Going to 315/70/17 tires on Willys JLU without "major" suspension modifications? 8B97EB8A-A9BC-4488-BABA-0F7D69B955F1
 

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Not to get off the rails on discussion, but I just picked these up for 200 bucks! They should help entry for my short second half once the 35” are on. Ace Engineered rail steps.

8B97EB8A-A9BC-4488-BABA-0F7D69B955F1.jpeg
Those are nice! We have these on both current Jeeps, and I had them on my previous one - Smittybilt, part number 77634. I’ve had the full weight of Jeeps resting on one of these, and have banged the hell out of them. They hold up really well, no dents so far! They also come with a piece to hide the pinch seam.

Jeep Wrangler JL Going to 315/70/17 tires on Willys JLU without "major" suspension modifications? DF55B459-81AA-4D17-A418-EAF205AD133A
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