35s to 37s with the same weight?

[MVOffroad]

I'm currently riding on a setup of some 35" x 76lb Toyo open country RTs. on 39lbs wheels. Hypothetically if I keep the weight of the wheels and tires the exact same, but jump up to 37s will there be any change in performance? What about If I get a heavier tire but a lighter wheel to offset and keep the same overall weight? I'd prefer not to go up in unsprung weight from my current setup and ideally shed some weight in the transition to 37s.

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[J0E]

I=∑mr2 so r (radius) increase as the square, that is weight at the tread is much more important that closer to the hub. rotational inertia only measurably impacts perf on dragsters at high acceleration, that's why the mag wheel was invented. But increasing the R increases the lever arm, so you'll have higher gears and lower performance. The Ruby D44's can handle 37's if you're easy on the skinny petal. The inertia of the tire/wheel combo is insignificant compared to the inertia of the vehicle. Jack your front wheel up and use your drill at to accelerate the wheel. Now put the vehicle on the ground and try the same. It's the mass of the vehicle, not the tire/wheel that matters.

If you crawl or like the looks of 37's get them. Milage will also drop, due mostly I suspect to increase aero drag.

What lift do you have?

 

[ohthatguy]

If it’s an aesthetics driven move, I’d consider a super wide 36” that’ll look better and not impact gearing as much (but they’re heavy). If you mainly want it to look better in profile, these 37’s are only 77.54 lbs;

BFGoodrich All Terrain TA KO2 37x13.50R18 (Load E)

 

[Zero_Accel]

I would recommend Yokohama Geolanders M/T G003, my 37x12.5/R17 come in at 76 lbs, 2 lbs LIGHTER than 35x12.5/R17 Toyo's, at least according to this site. And having to mount both brands tires on different Jeeps, I believe them. They look and perform very similarly as well.

I've had mine for about a year now with 10k miles, easily my favorite tire so far. Very quiet for a M/T, and they handle Rocks, Mud, and Sand like a champ.

 

[Zandcwhite]

A light tire and wheel can lessen the impact to performance, but all the other factors already discussed are still there. In my experience, axle shaft and or u-joint failures happen most often when a spinning wheel finds traction. That is 100% the inertia of the tire and wheel combo. I've broken more shafts and joints on a tall geared, low powered XJ on 35x14.50 pitbull tires than I care to remember. So far in JLUR's with massively deeper crawl ratios and anywhere from 35's to 38's that were far lighter running the same challenging trails we've broken nothing. Anecdotal for sure, maybe I pick better lines, definitely won't hammer the $60k rigs through the trails like I would the $6k rig, but I'm a firm believer in trying to keep the wheel and tire weight down.

 

[scj64]

Method wheels I’m looking at are 26.9 pounds and 37” KO2’s are 64.4 pounds. That kind of weight difference between what you have is very noticeable.

 

[MVOffroad]

I=∑mr2 so r (radius) increase as the square, that is weight at the tread is much more important that closer to the hub. rotational inertia only measurably impacts perf on dragsters at high acceleration, that's why the mag wheel was invented. But increasing the R increases the lever arm, so you'll have higher gears and lower performance. The Ruby D44's can handle 37's if you're easy on the skinny petal. The inertia of the tire/wheel combo is insignificant compared to the inertia of the vehicle. Jack your front wheel up and use your drill at to accelerate the wheel. Now put the vehicle on the ground and try the same. It's the mass of the vehicle, not the tire/wheel that matters.

If you crawl or like the looks of 37's get them. Milage will also drop, due mostly I suspect to increase aero drag.

What lift do you have?

I have the XR package Rubicon with aftermarket wheels and tires. Saw a vid on YouTube where a guy got 37s to work with no rubbing by just getting taller rear bump stop platforms.

 

[MVOffroad]

If it’s an aesthetics driven move, I’d consider a super wide 36” that’ll look better and not impact gearing as much (but they’re heavy). If you mainly want it to look better in profile, these 37’s are only 77.54 lbs;

BFGoodrich All Terrain TA KO2 37x13.50R18 (Load E)

Mainly looking for more ground clearance. Yeah I was looking at the KO2s but also considering the falken wildpeak at3ws

 

[grimmjeeper]

If you increase your tire diameter and change nothing else you make it harder for the engine to accelerate your Jeep.

Tire diameter changes is the biggest driver for changing gears. Weight is a secondary consideration. It's the reason you round up when you do the equation to figure out what gear is best.

New gear ratio = old gear ratio × new tire size ÷ old tire size

That being said, the JL has a transmission with a wide gear spread and a torque converter tuned to the engine. It has a tendency to mask a less than ideal gear ratio when you change tire size.

Will you notice a decrease in performance? Hard to say. Depends on a lot of factors, some of them are how you perceive things.

Best bet is to try the 37s. If you feel the Jeep becomes too sluggish consider regearing.

 

[jhackathorne]

Mainly looking for more ground clearance. Yeah I was looking at the KO2s but also considering the falken wildpeak at3ws

Get the Falkens over the BFG. I’ve ran both and live in CO as well, and I much prefer the Falkens. Softer tread compound is better in snow and ice.

I went from 35” Falken (30 psi) to 37” Maxxis (28 psi). Tires are same weight and I am getting about 2 MPG more on the 37”s somehow. Driving pattern hasn’t changed either and I tend to have a heavy foot. I do notice a TINY change in acceleration, but I am still happy with the performance on stock 4.10’s. I am running a Pulsar XT tuner however.

 

[MVOffroad]

Get the Falkens over the BFG. I’ve ran both and live in CO as well, and I much prefer the Falkens. Softer tread compound is better in snow and ice.

I went from 35” Falken (30 psi) to 37” Maxxis (28 psi). Tires are same weight and I am getting about 2 MPG more on the 37”s somehow. Driving pattern hasn’t changed either and I tend to have a heavy foot. I do notice a TINY change in acceleration, but I am still happy with the performance on stock 4.10’s. I am running a Pulsar XT tuner however.

Im leaning towards the falkens but they are a bit heavier than my current tire. If I do go with the falkens, Id get a lighter wheel because Im replacing my wheels anyway. I bought used and the previous owner put 20s on. I didnt know at the time that 20s werent ideal for wheeling. Which maxxis tires are you running? You like them?

 

[roaniecowpony]

I recently went to 37" Maxxis Razr AT with 4.88s in my JLUR with the 8sp auto. I think it's still pretty peppy. It's not even a noticeable decrease in performance when normal driving. I took a 200 mile round trip from the LA coast up the Cajon pass to Victorville and back over the weekend. Going up to the high desert, I got right at 15 mpg driving between 70 and 80+. Coming back down from the high desert I got right at 18 mpg driving between 75 and 80. (I have calibrated the speedometer to less than 1 mph, using JSCAN and GPS at speeds from 40 to 80 mph)

 

[jhackathorne]

Im leaning towards the falkens but they are a bit heavier than my current tire. If I do go with the falkens, Id get a lighter wheel because Im replacing my wheels anyway. I bought used and the previous owner put 20s on. I didnt know at the time that 20s werent ideal for wheeling. Which maxxis tires are you running? You like them?

I am running the same as @roaniecowpony; Maxxis Razr AT. They were a great price and get good reviews. I have had zero issues in them and they seem to perform well in snow also. They are louder than the Falken's since they are a hybrid tire, but not so loud that it bothers me.

 

[J0E]

A light tire and wheel can lessen the impact to performance, but all the other factors already discussed are still there. In my experience, axle shaft and or u-joint failures happen most often when a spinning wheel finds traction. That is 100% the inertia of the tire and wheel combo. I've broken more shafts and joints on a tall geared, low powered XJ on 35x14.50 pitbull tires than I care to remember. So far in JLUR's with massively deeper crawl ratios and anywhere from 35's to 38's that were far lighter running the same challenging trails we've broken nothing. Anecdotal for sure, maybe I pick better lines, definitely won't hammer the $60k rigs through the trails like I would the $6k rig, but I'm a firm believer in trying to keep the wheel and tire weight down.

In my experience, axle shaft and or u-joint failures happen most often when a spinning wheel finds traction

I don't think anyone will disagree with that.

That is 100% the inertia of the tire and wheel combo.

So the inertia of the 150 lb tire/wheel is more important than the inertia of the 4,500 bouncing vehicle? I don't think so. Bouncing is like a kinetic rope, now you've got more than the static weight contribution. Bouncing breaks driveline components no matter how light the tire/wheel combo is. It's just that taller wheels have a longer lever arm.

Spin your front tire (on a jack stand) 10 MPH and stop it. Now push your rig 10 MPH on a flat parking lot and try to stop it. Massive difference in inertia.

 

[Zandcwhite]

In my experience, axle shaft and or u-joint failures happen most often when a spinning wheel finds traction

I don't think anyone will disagree with that.

That is 100% the inertia of the tire and wheel combo.

Spin your front tire (on a jack stand) 10 MPH and stop it. Now push your rig 10 MPH on a flat parking lot and try to stop it. Massive difference in inertia.

MOST of those breaks, the vehicle has 0 inertia. The free spinning wheel coming to an abrupt stop is where the break happens. I guess if you look at it like the the sudden attempting to accelerate that 4500lb mass from 0mph up to the 10-30mph the wheel/shaft is spinning you could argue it is the vehicle and not the tire/wheel combo? Still doesn't explain why even the hp44 shafts and joints broke often under a heavy 35 in a rig that likely weighed 1500-2000lbs less than our JLURs though. Hugely less power and half the torque multiplication to boot. Obviously it's not proof of anything, but it's enough experience based evidence that you'll never find a set of nittos or other over weight tires on one of my Jeeps again.

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