33 inch tire minimum- Real, Guideline, or Urban Legend?

[JimBill]

I’ve been told, read on trail descriptions, and see some group run requirements state a minimum 33 inch tire is required to run a particular trail. Where does this “requirement” come from? Obviously a bigger tire diameter is helpful to climb over obstacles and such, but I do not know how seriously to weight this requirement when I see it.
My 76 Cherokee, with stock worn out springs, performed noticeably better off road with 30s than it does lifted with cheap stiff springs on 32s. My past Silverado trucks and present Tahoe with metric 32s and IFS cannot come close to my WJ with 30.5s in capability and comfort. Granted, you need enough lift to do what you need to do, but are 33 inch tires more important than flex, gearing, overall agility, brake performance, axle reliability, etc.?
I cannot go to a bigger tire on the WJ without mechanical and body mods or drastically limiting my suspension up travel. Am I eternally banned from joining groups on trails where the group lead has determined 33" tires minimum? (until I take the sawzall to the rig and upsize tires?). I'd take my WJ on 30.5s a lot more places than I would my Tahoe on 33's...….. so there is a lot more to it. I need an education on what “33 inch minimum tire diameter” really means to the community.

 

[madcratebuilder]

Generally taller tires need more gear ratio. I have not found anyplace I can't go on 32's. I would place more importance on tire tread, locked diff's, under carriage protection, approach, departure and break over angle. Taller tires do get the axles further off the ground, you gain a 1/2 inch for every inch of tire height.

 

[JimBill]

Generally taller tires need more gear ratio. I have not found anyplace I can't go on 32's. I would place more importance on tire tread, locked diff's, under carriage protection, approach, departure and break over angle. Taller tires do get the axles further off the ground, you gain a 1/2 inch for every inch of tire height.

I fully understand the virtue of a taller tire, and completely agree with you the rest of the rig matters more. A 33 tire on a Dana 60 vs 31 tire on a Dana 35, which has more clearance? It should not matter if your rig is otherwise capable. I'm wondering how 33 became the magic number, or is that a convenient guideline?

 

[4wheelspulling]

JimBill,
You ask a good question and yes, you are right when you say that there many other factors other than just tire size in off-road capability. I think when a trail says you need 33” tires to do the trail, that also takes into account the mods needed to run 33” tires? 33” tires on a CJ5 and 33” tires on a JKUL are a completely different game in capability! To be honest, I do not play in the rocks much, so, do not have a good handle on the 33” trail signs or requirements, just my opinion. Vance.

 

[tjZ06]

...are 33 inch tires more important than flex, gearing, overall agility, brake performance, axle reliability, etc.?...

No, not at all.

...I'd take my WJ on 30.5s a lot more places than I would my Tahoe on 33's...

Exactly. I think you already pretty much nailed this one, but a WJ on 30.5"s is going to do a lot more than a Tahoe on 33"s. The WJ just flexes so much better, being a solid front and rear axle rig with really well-designed coil-sprung multi-link suspension. I just did a trail with my Silverado ('11 2500) on 35x12.5-18"s that I would way, way, waaaaaaay rather have done in my WJ on 265/75-16 (~31.6x10.43") tires.

I would say if a trail description or trail-run organizer is putting saying 33" minimum for any rig imaginable, that's going to include IFS or even IFS/IRS rigs that are fully open front and rear diffs. A WJ on 30.5"s is easily going to do more than that theoretical IFS/IRS open-diff rig.

That said, I really, really, reaaaaaaaaally like how my WJ works on the 4" long-arm front (just springs/shocks/spacer with stock arm rear) kit. I had to do some trimming, and in fact have some more to do (as I think you've seen in other threads), but between that and the Quada-Drive it's super capable. It's also just fine on the stock 3.73s with these tires.

-TJ

 

[tjZ06]

JimBill,
You ask a good question and yes, you are right when you say that there many other factors other than just tire size in off-road capability. I think when a trail says you need 33” tires to do the trail, that also takes into account the mods needed to run 33” tires? 33” tires on a CJ5 and 33” tires on a JKUL are a completely different game in capability! To be honest, I do not play in the rocks much, so, do not have a good handle on the 33” trail signs or requirements, just my opinion. Vance.

Right. Or even more-over 33"s on a locked CJ5 is going to go way further than 33"s on a Gladiator.

-TJ

 

[JimBill]

"just did a trail with my Silverado ('11 2500) on 35x12.5-18"s that I would way, way, waaaaaaay rather have done in my WJ on 265/75-16 (~31.6x10.43") tires."


I know what you mean. The Tahoe did Surprise Canyon, Goler Wash, and Mengle Pass in Death Valley, and it was a constant battle to find the right line. I was mentally exhausted after a day of wheeling. The WJ did Cerro Gordo loop and Dedeckera Canyon over the steps to Eureka Dunes, and it was a pleasure. Bald Mountain Loop was just plain FUN in the WJ.

 

[Dilldog]

I have been on trails that people have labeled 33" minimum tire in a 1980 Isuzu pickup on 28" Super Swampers. It did just fine, but that was because I didnt care about body damage, it had GREAT under body protection, and I had a winch. Most of the time in my experience, "minimum tire size" is more a guideline that helps people plan when they are body damage adverse. I have gone lots of places in the old Isuzus where people said I needed a bigger tire, and 100% of the time they were right, unless you dont care about body damage. Also it depends on the type of people youre talking to, and what you drive. If its bunch of full sized guys and you drive a Jeep, you can usually get away with less tire due to increase maneuverability giving you more and better choice of lines through obstacles.

 

[slomatt]

I take those kind of "rules" as just a set of recommendations, and generally assume that they were thinking of 33" tires on a Jeep Wrangler. There are too many variations in terms of wheelbase, gearing, clearance, driver, etc to come up with hard and fast rules.

If it's a sign for a trail that is recommending 33" tires you can just ignore it and use your best judgement.
If a group has a rule that you have to have 33" tires to travel with them, well... then the best you can probably do is reach out to them and argue your point.

You can go pretty far on 32s, but definitely not on 31s. :)

 

[JimBill]

I plan to get to metric 32's, but as the last upgrade after a 3" lift. With this platform and a Dana 30 in front, I think 32s are the reasonable limit unless going full rock crawler and 6" + lift. But it will be a while. Have to swap the cooling system from hydraulic to mechanical/electric fans, add front end armor to protect the radiator, tuck the gas tank..... but I don't intend to ever have 33's on it.

 

[JCWages]

I have been on trails that people have labeled 33" minimum tire in a 1980 Isuzu pickup on 28" Super Swampers. It did just fine, but that was because I didnt care about body damage, it had GREAT under body protection, and I had a winch. Most of the time in my experience, "minimum tire size" is more a guideline that helps people plan when they are body damage adverse. I have gone lots of places in the old Isuzus where people said I needed a bigger tire, and 100% of the time they were right, unless you dont care about body damage. Also it depends on the type of people youre talking to, and what you drive. If its bunch of full sized guys and you drive a Jeep, you can usually get away with less tire due to increase maneuverability giving you more and better choice of lines through obstacles.

This!

 

[CurrentlyRockhoundin]

I’ve been told, read on trail descriptions, and see some group run requirements state a minimum 33 inch tire is required to run a particular trail.

What if you just show up and run it anyways? I mean its not like someone is going to walk around with a tape measure and check tires before hand, and I can't imagine a situation where someone says "HEY those tires are not big enough you can't come with us!" and if they did that may not be the group you want to roll with.

You know your rig best and if you come up to something that's too much for you to handle and you don't turn back or take a by-pass then it's on you.

 

[Smileyshaun]

Because stating a 33 inch tire as a minimum is a lot easier than saying “we recommend a 33 inch tire unless you have X vehicle with Y suspension , also your tire size can very depending on your wheelbase and axle size “
If you’re doing a large group run having everybody with at least a minimum tire size means that when you’re spotting through obstacles you can help people choose nearly the same line and it keeps things moving at a decent pace, a large group run can really get clogged up when the same person is getting hung up on most every obstacle . Also a lot of the reason most group runs will let you try and obstacle three times and then you need to get a pull or bypass.

But yes generally it is just a recommendation on trails but if the club sets a minimum tire size probably should stick with what the organizer of the event wants.

 

[tjZ06]

I plan to get to metric 32's, but as the last upgrade after a 3" lift. With this platform and a Dana 30 in front, I think 32s are the reasonable limit unless going full rock crawler and 6" + lift. But it will be a while. Have to swap the cooling system from hydraulic to mechanical/electric fans, add front end armor to protect the radiator, tuck the gas tank..... but I don't intend to ever have 33's on it.

Sorry, sort of off-topic but did you happen to write-up your e-fan swap?

-TJ

 

[Lindenwood]

I imagine this "guideline" is based entirely on the assumption that a certain level of committment and/or modification is required for most vehicles to run 33s. In other words, it is an arbitrary means to weed out those who are not "committed" to the "offroad culture."

 

[JimBill]

Sorry, sort of off-topic but did you happen to write-up your e-fan swap?

-TJ

Have only gathered some parts for the cooling fan swap, but have not dug in yet. Pulled a shroud with electric and the mechanical off of a 99 V8, and made the Rock Auto parts list. Last off road trip I did up the priority to before the rear differential swap. Tired of bouncing from 195 to 215 seemingly randomly with no control or adjustment of the system.

 

[JimBill]

Well I'm hoping a trail lead weighs in. Thank you all for your comments. Best I can tell when 33s are recommended it assumes a certain level of capability, and when trail leads "require 33s", it depends on their point of view. Here in Cali, if you want to play in the Sierras or out around Death Valley, you have to deal with at least some rock crawling. Mild to wild....

 

[grubworm]

i think tire size should match the driver's waist size

 

[JCWages]

i think tire size should match the driver's waist size

I'm 1" smaller than my tire size but I'm working on that.

 

[4wheelspulling]

Not to derail this thread, but I am in shape too, round is shape! Not sure I have seen a 34” tire advertisement! Vance.