Best Off Road tires for better FE, trucks need love too :)
Great article on tires for expedition use. Lots of knowledge that kind of goes against what most 4x4 folks say... And it would seem to be advice that justifies taller skinnier tires as true and capable off road choices. So for FE on a truck, less rolling resistance, less frontal resistance, less rotational mass, better fitment in wheel well (aerodynamics), less weight on suspension/drive-line components, etc etc.
Here's the link, and a few excerpts of interest for how a skinnier tire is just as good or better than a wider tire for a great deal of off road uses... Expeditions West: Tire Selection for Expedition Travel Quote:
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~C |
Tall skinny tires have many advantages both on-road and off-road, but they can have some disadvantages too. I have found that other features of a tire (tread pattern, sipes, compound, etcetera) are much more important than size. Also width should be considered in the context of vehicle weight and other factors.
Selection in some of these odd sizes is a big one. I wanted to get a set of the 255/85R16’s for their 33”+ diameter, but the only choices are mud terrains, or all terrains that look a lot more like mud terrains than anything else. Ended up going with 255/85R16 Cooper Discoverers, thinking they were all terrain, but they are definitely on the mud terrain side of the all-terrain spectrum. Put them on my 2001 4x4 Chevy 2500HD, absolutely hated how they did on road. (Note truck probably weighs 7000lbs.) Swapped over to Michelin LTX M/S2 285/70R17’s, I love them on the road, and so far they have performed better than you would think off-road. Next my 1991 Chevy 2500LD 4x4 got the 255/85R16 Cooper tires. It handled ok on-road with the tires, since this truck is probably only 4500lbs, but panic stops would send me spinning and/or into other lanes. The brakes weren’t the best, but the truck wouldn’t ever do this with the 265/75R16 Uniroyal Laredos that I had on another set of wheels and swapped back and forth. Since I got my 2005 Tacoma, I moved the 255/85R16 Cooper tires onto a spare set of Tacoma rims, but got a set of 235/85R16 Michelin LTX M/S2 for daily driving. Love the Michelins, truck is very confident and planted on bad road conditions. Will plow through standing water on the road from torrential downpours just fine. I recently did a swapout to do some offroading, so I had the coopers on the Tacoma for a few days. I didn’t push them on road, since I already knew what to expect, but they performed ok. They handled the offroading with ease, but honestly my DD Michelins would have done ok for what I did, since there wasn’t any mud or extreme terrain. Now for the MPG. My next fill up for the tacoma, which was ˝ DD tires and ˝ Offroad tires on mostly highway was 25.1 MPG, which compared to similar tanks that included similar offroading done with the DD tires (26.8 MPG used as reference), implies that the off-road tires would have accounted for a 3.4 MPG loss for half the trip (23.4). I had observed roughly a 3 MPG difference between the two tire sets on my 1991 Chevy, using only on road highway driving comparisons. (14 vs 17) I saw no MPG difference between the two tire sets on my 2001 Chevy, probably because the disadvantages of the mud terrain type tread pattern were offset by the extreme weight of the new wheels and tires. Roughly 20lb wheels and 35lb tires versus 30 lb wheels and 55 lb tires is a big difference. Also when you are only getting 11-14 anyway, differences are hard to discern. The moral of the story is: I don’t care how cool it is, I hate driving with mud terrains on pavement. Period. Edit: Oh, and all the numbers have been adjusted for differences in diameter. |
Agreed, mud terrains aren't worth it unless you see lots of mud! And there are certainly downsides to "skinny" tall tires... Especially if you drive your truck like a sports car hahaha. Tire folding is a very serious, and dangerous thing... But going with a tire that has a thicker and stronger sidewall can mitigate that to some extent.
From what I have read, the 285's are very popular in A/T for lots of expedition vehicles. The reason i like the opinions of the expedition guys, is because their trail rig is a street legal rig that gets them all over the world (including hwys and large cities). Thanks for some real world comparisons! I do think that it would be easy-ish to match mpg if one shopped around and tried their hardest to match the tire/wheel weight of the previous combo... ~C |
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In addition, a taller wheel leads to less sidewall... And in order to air down for driving off road, there needs to be more sidewall to allow for a greater contact patch to occur without slicing the rubber with the sides of the wheel. I believe the recommended aspect ratio for sidewall is +80% when airing down tires. ~C |
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Then too, with a larger tire diameter, you'd get a larger contact patch. In the extreme, consider a tracked vehicle, which has the same contact patch as a tire many yards in diameter. |
I think we should message interco and ask them when they're making the Super Swamper with LRR technology.
:D http://www.offroadadventures.com/upl...photos/593.jpg |
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You are correct that tire technology had not reached the point where low aspect ratios were common - or even possible. For practical purposes, plain jane bias tires can not be produced with an aspect ratio lower than about 75. If you add a belt (as in bias belted tires) lower aspect ratios become possible - but those weren't invented until decades after the invention of the automobile - and once you've started down a path, it's hard to introduce radical changes. |
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Example: Two tracks on sand, same size tire, one at 32psi a one at 10psi. Do you see the difference? One sinks and one floats. This is due to the ability to air down and increase surface area both in length and in width... With length being greater than width (you can see it's barely wider than the fully aired tire). http://i.imgur.com/qVJK2MD.jpg http://i.imgur.com/WIyxh0d.jpg Another issue, is that a larger wheel often means more weight than a smaller wheel with a taller tire... At least when it comes to AT and MT tires on trucks. You also have to consider the greater cost of larger wheels and corresponding rubber. Here is a side by side comparison between 15" and 17" wheels with I believe 37" rubber... I tried to find one with more likely 33" tires, but I couldn't. Quote:
As far as a comparison with a tracked vehicle, that's not even a remotely fair comparison. A tracked vehicle would be similar to having 4 or 5 smaller wheels on the vehicle, not having two larger wheels. Lets take a look, 30psi http://i.imgur.com/0ZlU2Ct.jpg 15psi http://i.imgur.com/o9y6V0m.jpg 7psi http://i.imgur.com/BUC91JT.jpg A tire capable of going to 10 or less PSI will most likely double it's contact patch, to accomplish that without airing down (or only airing down to about 20psi)... Well, you would need one seriously massive (tall) tire. I hope that shows that your tracked vehicle comparison is actually the reverse. An aired down tire is comparable to a track... A taller inflated tire is simply a taller tire. The main issue, is choosing a tire which is capable of airing down and then also behaving as you would expect it to on the road. My statement about sidewalls folding over was a disclaimer regarding on road driving habits/techniques. If you drive your truck like a sports car, hitting twisty roads, death turns, etc, then you should get a lower aspect ration side wall and anticipate a reduced ability to air down on the trail (or so I would assume). Then again, if you are an ecomodder... You shouldn't be driving like a bat out of hell anyway :rolleyes: :D ~C |
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