Since I received such good advice on suspension, I would like to poll the group on tire selection. What is an all around good tire size wise and why? What are some of the advantages of going with taller and skinnier (is that a word?) as opposed to wider? I don't know if there is already a thread dedicated to this but if so, my apologies.
Thoughts on tires, tall or wide, advantages?
- Thread starter colotaco
- Start date
SOAZ
Tim and Kelsey get lost..
colotaco said:
I think there have been a couple of threads on here, but check this link out. Some rational info on the subject:
http://www.expeditionswest.com/research/white_papers/tire_selection_rev1.html
I like 255/85/16's for what I do.
Desertdude
Expedition Leader
bigreen505
Expedition Leader
Wider tires look better. Beyond that I'm having trouble with positives. I moved from a 285/75 to a 235/85 and I am quite happy with them.
4AFK
Observer
bigreen505 said:
Wider tires tend to perform better in situations where you're passing through soft materials like sand. Additional surface area is helpful in this case because it "floats" your heavy vehicle and gives you a little extra to grab onto. Narrow (usually hard compound tires) are excellent for passing over clay and rocky soils. These kinds of surfaces won't give way as often or as deeply as the sandy stuff so the extra surface area isn't really required and the harder rubber compounds allow you to grip in these conditions far better. Or at least that's the way I understand how it works.
Personaly, I think that narrow tall ties look better on most rigs than wider tires. Guess it really depends.
bigreen505
Expedition Leader
4AFK said:
In my limited experience that only really holds true if you have enough power to push a wide tire.
Okay. I've been debating this recently (not to totally thread hijack - its related)
I have a heavy, full-size truck with 285/70/17 BFG ATs. These are great for me around town, fantastic on highway, and superb for the off road driving I do in the dirt and mud. I'm getting around on rough trails, steep mountain dirt roads, backcountry trails, etc... but nothing extreme. These tires are also great in the snow... As long as it isn't really deep packed snow.
Recently there have been a couple of instances where I'm not high-centered, but am on packed, deep snow. Any combination of gearing, rocking, etc will just dig me deeper in. Four nice holes. This isn't a result of poor modulation or just givenherhell on the throttle. I have years experience driving in deep snow, packed or not. However, this is my first attempt with a full size [read: heavy] truck.
I have this suspicion that a more narrow tire will give me better "bite". Am I being absurd? Will this truck just dig 4 smaller holes? Or will I move better?
IE - the same "tallnes" (diameter) of tire yet overall more narrow width...
Thoughts?
I have a heavy, full-size truck with 285/70/17 BFG ATs. These are great for me around town, fantastic on highway, and superb for the off road driving I do in the dirt and mud. I'm getting around on rough trails, steep mountain dirt roads, backcountry trails, etc... but nothing extreme. These tires are also great in the snow... As long as it isn't really deep packed snow.
Recently there have been a couple of instances where I'm not high-centered, but am on packed, deep snow. Any combination of gearing, rocking, etc will just dig me deeper in. Four nice holes. This isn't a result of poor modulation or just givenherhell on the throttle. I have years experience driving in deep snow, packed or not. However, this is my first attempt with a full size [read: heavy] truck.
I have this suspicion that a more narrow tire will give me better "bite". Am I being absurd? Will this truck just dig 4 smaller holes? Or will I move better?
IE - the same "tallnes" (diameter) of tire yet overall more narrow width...
Thoughts?
Scott Brady
Founder
brettf said:
Once the surface mediums depth exceed 110% (like really deep, soupy mud or snow) or so of your available ground clearance, the only option you have is to float, which is a wide and tall tire, aired way down to distribute the weight of the vehicle over a much larger surface are (think tank tracks).
Redline
Likes to Drive and Ride
Not as technical as Scott's answer but I have done lots of travel in heavy full-sized diesel trucks. I have mostly used 255/85R16 tires. When it gets soft the big trucks tend to sink because of the weight, and I don't think my tire or your tire size has a big advantage.
The answer is: what Scott said
The answer is: what Scott said
brettf said:
expeditionswest said:
O.K. Scott,
I am not a hard core rock crawler (in that I mean besides a bulbar and rear tube bumper I don't see me needing rock sliders or other armor) just want to make my truck an expedition rig that will get me to most places in Colorado and Utah to climb, mountain bike, and shoot photo's. I have BFG AT 31x10.5 15's now, I want to go up one size to a 32x11.5 15 AT what am I gaining? What am I losing?
After reading these threads, I consider your thoughts as gospel.
DaveInDenver
Middle Income Semi-Redneck
You can generalize that the wider with ultra low air pressure is better on soft surfaces, like fresh snow, powdery sand or thin mud. On pavement, I also agree that narrower with relatively high pressure is almost always preferred for less rolling resistance and better bite on thinner layers of snow or rain covered roads. Those two cases are the ends of the spectrum, one case you want to spread your truck's weight over maximum area and the other you want to concentrate the weight on enough rubber to keep from sliding off the road.
But on other surfaces a narrow or wide tire isn't always clear. It depends on how much your truck weighs, the air pressure you run and the contact patch of the aired down tire. So for example I run a 9.50 section width x 33 tall tire on a 5,000 (loaded) truck. On 15" rims with that weight I typically run about 16 psi, give or take depending on the amount of rocks. Anyway, I seem to get a nice bite since I'm not running too much contact patch and so I get a good force per unit area. A 12.50 section width tire would give me considerably less force/area (say lbs/sq-in) at 16 psi and with a relatively light truck that could mean I don't have enough friction and spin the tires more often. I figure at some point I will go to a 33x10.50 (since they don't make a BFG MT in 9.50 width) and so I will probably air down to 18 psi to keep the weight more concentrated on a smaller contact patch. With a super wide tire, I would consider even 20 or 22 psi, although at some point you need deformation of the tire to get traction around features.
When you hit that point the method by which you are getting friction is slightly different. You are relying on a few prominent points where a single knob or two are biting and not the whole distributed tread/surface interface. The reason the 33x12.50 tires work so well is because you are often running very low pressures and the tires are wrapping around more features. That's fine (and necessary) for rock crawling, but when you are talking about general purpose traction on more uniform terrain, you need to run sufficient contact patch pressure that gives you enough traction, but without very high rolling resistance and still avoid sidewall failures and handling impacts of very low pressures. Not all trails require true rock crawling and so having a tire with the right amount of sidewall bulge to controllably support the weight is important. For 4WD high and 1/2 type trails I run around 25 psi.
For me the ideal tire seems to be 33x9.50 on general use with the main downside being deep snow. I sink like a rock. I think a 33x10.50 will be a nice tire as I move away from using my truck as a daily driver and so it does not have to handle snowy roads as often. For colotaco, I think a 32x10.50 or 33x10.50 is the right size for you here. Just my $0.02.
But on other surfaces a narrow or wide tire isn't always clear. It depends on how much your truck weighs, the air pressure you run and the contact patch of the aired down tire. So for example I run a 9.50 section width x 33 tall tire on a 5,000 (loaded) truck. On 15" rims with that weight I typically run about 16 psi, give or take depending on the amount of rocks. Anyway, I seem to get a nice bite since I'm not running too much contact patch and so I get a good force per unit area. A 12.50 section width tire would give me considerably less force/area (say lbs/sq-in) at 16 psi and with a relatively light truck that could mean I don't have enough friction and spin the tires more often. I figure at some point I will go to a 33x10.50 (since they don't make a BFG MT in 9.50 width) and so I will probably air down to 18 psi to keep the weight more concentrated on a smaller contact patch. With a super wide tire, I would consider even 20 or 22 psi, although at some point you need deformation of the tire to get traction around features.
When you hit that point the method by which you are getting friction is slightly different. You are relying on a few prominent points where a single knob or two are biting and not the whole distributed tread/surface interface. The reason the 33x12.50 tires work so well is because you are often running very low pressures and the tires are wrapping around more features. That's fine (and necessary) for rock crawling, but when you are talking about general purpose traction on more uniform terrain, you need to run sufficient contact patch pressure that gives you enough traction, but without very high rolling resistance and still avoid sidewall failures and handling impacts of very low pressures. Not all trails require true rock crawling and so having a tire with the right amount of sidewall bulge to controllably support the weight is important. For 4WD high and 1/2 type trails I run around 25 psi.
For me the ideal tire seems to be 33x9.50 on general use with the main downside being deep snow. I sink like a rock. I think a 33x10.50 will be a nice tire as I move away from using my truck as a daily driver and so it does not have to handle snowy roads as often. For colotaco, I think a 32x10.50 or 33x10.50 is the right size for you here. Just my $0.02.
DaveInDenver
Middle Income Semi-Redneck
Where have you been reading the reviews? What sorts of negatives things have you been hearing about the AT? A whole heckuva lot of people have BFG ATs and MTs, so just wondering. I've personally had several sets of ATs and MTs and only one single tire would I consider defective and that was replaced under warranty with no questions asked. I generally get in the 30,000~40,000 mile range from a set.colotaco said:
BigAl
Expedition Leader
I've often heard that skinny tires give better traction, but I can't figure out why the pros use wider tires. Desert race trucks, rock crawlers, sprint cars, mud boggers, late models all use wider tires. You might say that race vehicles are big horsepower, but some rock buggys use 75 hp saturn motors???? Except for the steering wheels on a swamp buggy, I can't think of an offroad race vehicle with skinny tires. Generally racers use whatever will give them an advantage????