40’s only for rock crawling?

[Yellowstone]

I understand why larger tires are better for crawling over obstacles and rocks. But would larger tires also be beneficial when it’s comes to smoothing out the ride on easy and/or very long off road trips?

I‘m planning a suspension upgrade this winter along with 37’s. Not withstanding the need to upgrade even more components to run 40s, would running those larger tires make washboard and heavily cobblestoned trails more comfortable when covering 100+ miles/day? Or are 40s for rock crawling only?

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[Headbarcode]

I understand why larger tires are better for crawling over obstacles and rocks. But would larger tires also be beneficial when it’s comes to smoothing out the ride on easy and/or very long off road trips?

I‘m planning a suspension upgrade this winter along with 37’s. Not withstanding the need to upgrade even more components to run 40s, would running those larger tires make washboard and heavily cobblestoned trails more comfortable when covering 100+ miles/day? Or are 40s for rock crawling only?

First off, what model wrangler do you have and how is it specced out? Any mods so far? The devils in the details.

In my opinion, tire pressure and choice of shocks have more control over ride comfort in the rough. Tire diameter and width more determines how big of a contact patch you can use for grip or floatation.

 

[Gorilla57]

In my opinion, tire pressure and choice of shocks have more control over ride comfort in the rough.

Agree. Plus I’ll add, a good suspension setup is a must. I went with the RK long arm setup just for that reason. Trails in AZ are down dirt roads, sometimes many miles from the pavement. I’m running beadlock 37’s, RK long arm and ADS shocks. This thing is amazing at 12psi in the washboard roads around here.

 

[Yellowstone]

It’s a JLUR on stock axels now. But in a thread I started on the suspension forum, I’m looking at a long arm kit this winter and probably coilovers on 37s and a regear. My guess is that this will get me at least 90% of the way. Of course the cost to get the last 10%, if 40s will get me there, is very high (new axels, etc).

But if folks say that, no, 40s will actually improve off road ride quality 25% in my circumstance...then maybe thats something I can look at later, but try to prepare for now with a mind for doing it down the road.

So that’s the core of the question. how Much of a difference between a 37 and a 40 can be expected due to the larger diameter and taller sidewall on flat roads?

 

[Sting_NC_USA]

Have to agree with the others, 40's are not the key ingredient to smoother off-road travel. Unless you're looking for support to coerce the significant other into "blessing" 40's, high quality tires on rims no bigger than 17 inches, with a higher-end lift and shocks, will get you everything you're describing. 40's are a major investment, as you've noted, well beyond the cost of the tires.

 

[ChattVol]

I understand why larger tires are better for crawling over obstacles and rocks. But would larger tires also be beneficial when it’s comes to smoothing out the ride on easy and/or very long off road trips?

I‘m planning a suspension upgrade this winter along with 37’s. Not withstanding the need to upgrade even more components to run 40s, would running those larger tires make washboard and heavily cobblestoned trails more comfortable when covering 100+ miles/day? Or are 40s for rock crawling only?

No...40s arent gonna help. Proper spring/shock pairing, castor angle and airing down offroad is what I would focus on.

 

[Toycrusher]

I'm going to take quite the contrary position.

Bone stock suspension, there is a TREMENDOUS improvement in ride quality moving from 33" KO2s to 37" KO2s. I think many people credit their lift and shocks for the improvement in ride, when it's really the tires.

It's simple physics really, a bump or dip becomes proportionally smaller in relation to tire diameter and mass. Moving from 37s to 40s will have an additional benefit.

Do you need to upgrade axles? All depends on what you are doing with it. If your usage is primarily poorly maintained "roads" and not rockcrawling, you can get away with a lot. Keep in mind you will definitely want to regear, and you will have a longer braking distance than stock, and you will have a tougher time steering on anything not paved. Your fuel economy will most certainly take a beating which, in the scheme of things, ($55-$70k invested in your Jeep) means diddly squat.

Will it look cool? Yes. Will it ride better? Yes

 

[Revolution_322]

This thread is proof that this forum is for complete white belts.

 

[Toycrusher]

This thread is proof that this forum is for complete white belts.

Um? What color belt did YOU start with?

 

[Revolution_322]

Um? What color belt did YOU start with?

White but like when i was 17.

 

[Toycrusher]

White but like when i was 17.

Same here, my first rig I built in my parents driveway at 16. Worked nights, slept in class to pay for it. '84 Ranger, swapped in 5.0, TTB lift, 33s, frankenstein C4/C5 transmission, and more.

I am of the opinion it's NEVER to late to get bit by the 'wheelin bug. Start with a white belt, get it greasy and muddy, and go from there.

 

[Yellowstone]

Thank you all for your comments and feedback. Toycrusher, your thoughts make perfect sense to me. I think it sounds like there would be an incremental improvement, there would have to be from purely a physics standpoint, but that suspension is a proportionally much larger role in ride comfort. So I’ll build out for 37s to start and wear out a few sets of tires and see how that goes. Chances are 37s will be great!

 

[AnnDee4444]

"Ride quality" can have different meanings to different people. My biggest concern with heavier tires is the increase in unsprung mass.

From Wikipedia:

The unsprung mass of a wheel offers a trade-off between a wheel's bump-following ability and its vibration isolation. Bumps and surface imperfections in the road cause tire compression, inducing a force on the unsprung mass. The unsprung mass then reacts to this force with movement of its own. The motion amplitude for short bumps is inversely proportional to the weight. A lighter wheel which readily rebounds from road bumps will have more grip and more constant grip when tracking over an imperfect road. For this reason, lighter wheels are sought especially for high-performance applications. However, the lighter wheel will soak up less vibration. The irregularities of the road surface will transfer to the cabin through the suspension and hence ride quality and road noise are worse. For longer bumps that the wheels follow, greater unsprung mass causes more energy to be absorbed by the wheels and makes the ride worse.​

 

[SSWIM]

Absolutely tire diameter will play a role in the handling characteristics. If one doesn't believe so take a look at the progression of the TTs in desert racing. 40s are the norm now. Of course proper suspension set up is a must. But the diameter will help very much.

Sam

 

[SSWIM]

We will have to agree to disagree on that one.

Sam

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