Wondering Why Duratrac's?
- Thread starter KonaHI808
- Start date
offroadingatc
New member
I think i might try dropping the pressure again, since putting it up didn't really do much for my mileage. I was getting mid 13's before and now I'm in the mid 15's (17 then 15 mpg for those who care) My truck still thinks its getting 13 l/100, so Im not sure whats up with that. I lost about 1l/100 in the fall when they switched to winter blend so i should get that back soon.
I was running 36 when they installed them but they felt really squishy actually softer than stock tires, and they looked really 'flat'. Putting them up made it feel firmer, but Im not crazy about them wearing unevenly either.
my mileage data is here https://docs.google.com/spreadsheet/ccc?key=0AnqT_wq98oBvdElyQngwZ01va2hDUjJiUExPUGhVd3c#gid=0
JB.
New member
Just curious what persuades you it's a great highway tire.
Ryan_S
New member
Handling at higher speeds. I typically drive 75 to 80 mph to work and the tires don't feel "squishy" or they don't vibrate or shake the vehicle. They do have a noticeable hum, but it's nothing obnoxious.
High speed lane changes and swerving don't make the tires howl or start to lose grip.
I can compare this to the snow tires I used to run on my WRX. They were not really good dry pavement highway tires, soft compound, tall tread, etc. They were squishy changes lanes and you could make them howl or squeal by swerving aggressively.
Stu-Runner
Member
I will freely admit that I was initially drawn to the Duratracs for looks and this Forum. They are really sweet looking and completely change the look of the truck.
I was a die-hard BFG AT guy....had a set on all my trucks. However, after putting the DT's on I am very pleased. I have only had the tires on since January so I am not sure what to expect long term. The reviews and ratings for the DT's were very good. Plus for such and aggressive tread, the weight (C rated) was not terrible, it's 43lbs each.
To continue the thread hijack... I have been curious about the correct tire pressure. I have been running the stock rating of 32 psi since I kept the stock tire size (265/70/17). Looks like some guys are running a little higher to help with mileage but at the cost of possible uneven wear.
Obviously my MPG has decreased, so I wouldn't mind gaining some back with increased tire pressure. Prior to lift and tires, on the highway I would see between 20 and 21 mpg. Now I am seeing 16.5 to 18.0.
Stu
Ryan_S
New member
Pressure is based in load and rating, not necessarily size. You now have LT, which warrants higher pressure.
I keep mine at 44 (load range E tho). But I don't have uneven wear.
TreeFarmer
New member
Duras look great. The tire store manager talked me out of them. He has them on his suv and said they are a little squirrelly in the rain we get in the NW. I had the bfg at for 60k. Not overly impressed in the snow or mud. Not going to put them on again.
JB.
New member
It's an open question but keep in mind that a same size LT requires about 12psi to carry the same load as the stock P-metric tire. Put another way, at 32psi the new tire load capacity dropped by more than 300lbs per tire.
That still leaves load reserve, on paper, even at GVW, but much less than before. Load reserve (as well as speed reserve) are good things since tires don't get stronger with age.
Since the higher pressure is the load carrying equivalent of the stock tires, I'd expect much better wear at 44psi than 32psi.
higher LT pressure
I bought LT Revo on my last vehicle not knowing about the extra pressure required but I ran them for 50k+ miles at 34psi (OEM 30psi) no towing. This probably explains the additional wear of the edges but not too bad. If LT tires have stiffer sidewalls can someone explain to me why it requires higher pressures. I'm just trying to understand. Thanks.
I bought LT Revo on my last vehicle not knowing about the extra pressure required but I ran them for 50k+ miles at 34psi (OEM 30psi) no towing. This probably explains the additional wear of the edges but not too bad. If LT tires have stiffer sidewalls can someone explain to me why it requires higher pressures. I'm just trying to understand. Thanks.
scanny
Senior Member
I tired 40 psi and found that about 1 inch on the tire edges don't touch the ground. There is a lot of salt covered road around in the winter easy to make sort of a chalk test. But with the time at 40 psi center will wear out and whole tread will touch the ground, so probably it's not that bad.
Koz
New member
When are you checking/adding pressure (cold or after a short drive)? Also, what model tire do you have? I've done several chalk tests and mine has full contact at 40 psi. At OEM pressure I have sidewall contact at highway speeds!
Koz
I am sure JB and others can explain this better than I, but years ago I had the same question and somebody explained it to me like this. Think of tires like balloons. The balloons you can blow up with your mouth are very thin, thus it takes less pressure to get them expanded to the proper size. Try blowing up a bicycle inner tube with your mouth. Can't do it. Why? Too thick. Yea, you will get some air in there, but not nearly enough to use on your bike.
"P" rated tires are "thinner", thus less air to get them up to useful inflation.
C,D,E etc thicker. Needs more air.
Not a great analogy, but it made sense to me at the time.
1engineer
Moderator
Two reasons:
An LT tire has a stiffer construction. It is designed to carry a higher load than a "P" rated tire. A higher pressure is required to carry a heavier load and also to properly inflate the tire to it's correct "shape" due to additional plies and stiffness.
Think of it like this: Let's say your tire has a contact patch of 100 square inches. I really don't know what it truly is but 100 will make the math easy to follow along. And contact patch is simply the area of the tire that is in contact with the road at any one time. OK, so we have 100 square inches (pay attention to the units here) and we inflate the tire to 30 psi (pounds per square inch). That means we have 3000 pounds of force holding the truck up off the ground. If I inflated it to 40 psi then I have 4000 pounds of force holding it up, etc. In this example you can see how higher pressure can increase load capability. Again I do not know what our 4Runner's actual numbers are as I was just showing an example.
In addition to tires having the capability to contain the correct amount of pressure to do the work they also must be able to have the correct cross sectional shape while doing this. For example, too much sidewall flex under load will cause heat, in addition to increased contact patch caused by the flex. This could cause the tire to prematurely fail. To counter this, an LT tire has stiffer sidewalls and additional plies designed to safely accommodate the additional pressure and load. Underinflation of a tire can cause the same conditions as overloading a tire. At least you will get uneven and excessive wear and worst case failure. Hopefully this explains to you the basic mechanics of a tire.
Koz
New member
The construction of each type of tire dictates how much pressure is required to carry a certain amount of weight. LT tire are designed carry more weight and require more pressure. You may need more pressure in a LT tire to carry the same weight as a "P" tire. A "p" tire will max out at approx 41/44psi (max load 2600 lbs) where as a LT tire will max out at 80 psi (max load 3400 lbs). Every pound below max will reduce the load by so many lbs. Not enough pressure for the load can damage the tire and depending on the application, could be dangerous. Example; the pressure in trailer tires is VERY critical. I've seen all the tires on a trailer blow out in one trip because they were overloaded. Heat and pressure build up and KaPooy! Remember for every 10 degrees of heat you gain 1 psi. At highway speeds (and/or excessive speed) on an underinflated tire the heat/pressure could go up pretty quick.
Notice on this aftermarket TPMS system they give you real time pressure AND temperature.
tst systems
Koz
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