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-   -   Off road on your 20s? (http://www.jeepgarage.org/f109/off-road-on-your-20s-48308.html)

DirtyDuc83 10-03-2012 01:34 PM

Off road on your 20s?
 
I see a lot of threads about people going with ATs on their 20's, generally in the 275/55/20 size. Any of ya'll actually going off road with them? How did they do? Any issues you've run in to?

I went with 285/50/20s and have done some light off roading and they seemed to do fine. Just concerned with the short sidewalls and airing down/pinch flats etc...I know going with an 18 wheel would be a much better choice and I am in the process of trying to sell my OEM 20s and pick up a set of 18s. In the meantime, running my SRT8 reps and Falken Rocky Mountains need to suffice for now.

Any pics with some of the terrain you've tackled on 20s?

Schweibs 10-06-2012 02:58 PM

I don't have 20s but I bet if you stayed away from rocks you should be fine. The perfect set up would be to have street tires on your 20s and have a set of 18s wrapped in mud tires. But yea I wouldn't worry a lot about wheeling with 20s, plus you are running 285/50 so you have more sidewall.

DirtyDuc83 10-06-2012 03:06 PM

Re: Off road on your 20s?
 
Quote:

Originally Posted by Schweibs (Post 693343)
I don't have 20s but I bet if you stayed away from rocks you should be fine. The perfect set up would be to have street tires on your 20s and have a set of 18s wrapped in mud tires. But yea I wouldn't worry a lot about wheeling with 20s, plus you are running 285/50 so you have more sidewall.

Yeah, I didn't have any problems on a few fairly rutted trails with some rocks jutting out of the dirt. I didn't air down and did just fine. The ride was definitely stiff though.

I've just seen a lot of posts about people putting on bigger AT tires on their 20s, but not many reports of how well they did or the terrain they conquered with them on. I want to get a frame of reference as to how difficult of a trail I could handle with the 20s.

I have my 20s posted on CL, so as soon as they sell, a set of 18" MB Torque's are in my future.

Dollar 10-23-2012 10:14 PM

Search for my road trip that involved plenty of off roading. I did fine with my 275's. I'd link the thread, but I'm on my phone.


Sent from a pay phone.

Alaska-HWY JK 10-23-2012 10:57 PM

Re: Off road on your 20s?
 
You're not going to air down 18s a whole lot either, you're only gaining an inch of sidewall. On my JK with 18s I'd drop to 15 at the lowest and that was with a 305/65/18 which is almost a 34" tire. We haven't tried the wife's Overland with the 275/55/20 Silent Armor yet. The stock 18s made it through Soldiers Pass and Broken Arrow in Sedona OK. The Silent Armors will get snow and ice tested as its been coming down all week. I air my 37s down to 8 or 9 psi with 17" rims and no bead locks.

spyder873 10-24-2012 02:05 AM

Re: Off road on your 20s?
 
I will have to look but I believe Offroad Mag. did a report a while ago and about wheelin with 20's and found out you get more contact area with them compared to 15's ( I believe that was the size they tested against).
The down fall was the price of the tire and what was available at the time. They had Tire contact patches and everything.


I will try to find the article when I am more awake

spyder873 10-24-2012 08:08 AM

Re: Off road on your 20s?
 
Crap .... I will keep looking but basically when doing a contact patch test , They found that the larger rim size allowed more of the tires tread to touch the rocks then the 15, which folded over and left a larger portion of the center of the tire not touching the rock.

The trick is sidewall size, you still want a larger sidewall to flex and grab , This will also let you run them at a lower PSI then a smaller sidewall and will protect the rim better.

The advantage to a smaller rim is you will get a little better ride ( cushion ) offroad and the tires are cheaper.

Sorry , I am doing this all from memory .so bear with me until I can find the article.

Schweibs 10-24-2012 08:54 AM

Quote:

Originally Posted by spyder873 (Post 701820)
Crap .... I will keep looking but basically when doing a contact patch test , They found that the larger rim size allowed more of the tires tread to touch the rocks then the 15

Umm what? I'm sorry but I'm confused

spyder873 10-24-2012 09:05 AM

Re: Off road on your 20s?
 
I cant find the article but here is the basic concept


(__^__) = 15" It would bubble in the center of the tread pattern . so the center of the tire would not contact the surface of the rock ( or whatever)

(_____) =20" where as the 20" tire being it is on a larger rim has more support on the outer edges causing the Tread footprint to stay wide ( not buckle in the middle) giving you more tread area in contact with the surface of the Rock ( or whatever)

I am still looking for the article. I hope that explanation is alittle better .

spyder873 10-24-2012 09:12 AM

Re: Off road on your 20s?
 
Just like on the road , a 20" rim tire is more stable ( doesnt flex as much) as a 15" rim tire . that is one reason why all the car mfg's are going to the bigger rims and smaller sidewall tire

canis 10-24-2012 09:18 AM

Re: Off road on your 20s?
 
Hmmm...still confusing. If the trick is sidewall size (which it is), then the only thing you can do with a constant OD is have a smaller ID (i.e. smaller rim). And the (______) example only shows that you would have maximum contact if the rock is flat, which very few are. Assuming a constant OD, I can't imagine how a 20 would be better than anything smaller. I'm interested to see this article you are referencing.

Schweibs 10-24-2012 09:21 AM

Quote:

Originally Posted by canis (Post 701852)
I can't imagine how a 20 would be better than anything smaller. I'm interested to see this article you are referencing.

x2


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