Wondering Why Duratrac's?

Koz said:
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
Click to expand...

Got LT C load stock size Duratracs. They go up to 50psi, but I found that at 36 cold I have best traction. My test was easy, fill them up to 40 psi when they are cold, after coming to work check tires and they all white except about 1 inch on the edges.

at 36psi front tires all white, rear tires are black for 1/4 inch from sides. Guess rear tires would make full contact if truck is loaded.

So I wouldn't go over 40psi for LT tires unless it's dry and you want to save on fuel.
60 psi for LT tires might be good for full size truck like Tundra, but for 4Runners I think it's overkill.
 
scanny said:
Got LT C load stock size Duratracs. They go up to 50psi, but I found that at 36 cold I have best traction. My test was easy, fill them up to 40 psi when they are cold, after coming to work check tires and they all white except about 1 inch on the edges.

at 36psi front tires all white, rear tires are black for 1/4 inch from sides. Guess rear tires would make full contact if truck is loaded.

So I wouldn't go over 40psi for LT tires unless it's dry and you want to save on fuel.
60 psi for LT tires might be good for full size truck like Tundra, but for 4Runners I think it's overkill.
Click to expand...

It all depends on the tire style (each tire is different, load rating), the conditions in which you drive and your driving style. My testing was with "E" rated highway M&S tires.

I'm running 35F/40R on my IS (Z rated), works great!

Koz
 
So for an E-Load Duratrac on the highway not towing, what should I have them inflated to? I think mine are around 45PSI right now but am a little concerned after reading this thread. I'm more worried about tire longevity than fuel mileage if I had to choose.
 
msommers said:
So for an E-Load Duratrac on the highway not towing, what should I have them inflated to? I think mine are around 45PSI right now but am a little concerned after reading this thread. I'm more worried about tire longevity than fuel mileage if I had to choose.
Click to expand...

You would have to experiment with the pressure. First find a high pressure starting point that doesn't cause a harsh ride (maybe 60 psi when cold). Take the vehicle for a ride (several miles) to get the tires up to operating temp (the pressure will increase). Then stop Draw a 2 or 3 inch line across the treads and a couple inches up the sidewalls with chalk and go for another ride that mimics your normal driving (the driving that you do the most). Then stop and check where the chalk has worn away. The ideal pressure will be a highest pressure that has worn away the chalk only on the treads (not the sidewall). If the chalk is not worn to the edge you will need to remove some pressure (Maybe 2 lbs), re-chalk the tire and travel the same route. If the chalk is worn on the sidewall and/or not worn in the middle of the treads you need to add pressure.

Koz
 
You guys are running high pressures.
The max pressure on the side of the tire is to carry the max weight. Less weight, less pressure. Also the larger the tire, the more weight it can carry at the same pressure as a smaller tire. Hence, bigger tires require less pressure to carry the same weight.

If you want to figure out the pressure that will be best, do the chalk test.

Go to a parking lot, rub chalk across the tread of the tire, drive straight for a short distance, check the chalk, if it is rubbed off more on the shoulders you need to add air, if it's rubbed off in the center-less air. Adjust till it looks consistent across the whole tread.

I run a few pounds more than the door jam says.
 
msommers said:
So for an E-Load Duratrac on the highway not towing, what should I have them inflated to? I think mine are around 45PSI right now but am a little concerned after reading this thread. I'm more worried about tire longevity than fuel mileage if I had to choose.
Click to expand...

If they're the same "size" as the stock P265/70/17 (technically, going to LT qualifies as a size change), the logical starting point is about 44psi which matches the load reserve of the stock tire at door sticker pressure. If the new tire is bigger, that equates to even more load capacity per psi, so, in either case, you have nothing to worry about.

As far as chalk tests, I question the usefullness on an off-road tire. Ultimately, time and wear tell the real story, and higher pressure is much less likely to cause wear problems than lower.
 
JB. said:
If they're the same "size" as the stock P265/70/17 (technically, going to LT qualifies as a size change), the logical starting point is about 44psi which matches the load reserve of the stock tire at door sticker pressure. If the new tire is bigger, that equates to even more load capacity per psi, so, in either case, you have nothing to worry about.

As far as chalk tests, I question the usefullness on an off-road tire. Ultimately, time and wear tell the real story, and higher pressure is much less likely to cause wear problems than lower.
Click to expand...

I may stand corrected. Is the factory recommended pressure for the stock tires 44psi?

As far as the chalk test goes. It shows wear at an accelerated rate and works for street and offroad tires.
 
JB. said:
I don't own a 5th gen but I believe it's 32psi.
Click to expand...

I think some of these guys get confused, and I can see where it would be easy to do I suppose. The door says one thing, the OEM tire says another and then they step out on a limb and buy a LT tire and it says something else entirely. And then to top it off it was 20 degrees here monday night and 72 degrees this afternoon. That is approximately a 5 psi swing! Best thing for them to do is run their "P" rated tires at door sticker. LT tires run higher. How high? Depends on the load. Call the manufacturer for their input. I have.
 
Gerdo said:
I may stand corrected. Is the factory recommended pressure for the stock tires 44psi?

As far as the chalk test goes. It shows wear at an accelerated rate and works for street and offroad tires.
Click to expand...

Factory recommended is 32 psi, and by the way 44 is the maximum psi for stock Bridgestones.

I asked Goodyear for recommended Duratracs tires inflation, Goodyear said to inflate according to the load and send me load inflation table for LT tires.
 
I am running the C rated 265/70/17 DuraTracs and when I had them installed the tire tech recommended running 32 psi which is what is on the door sticker for the stock bridgestones.

I was somewhat skeptical running the 32 psi and assumed I may need additional psi.

After reading the replies from the guys (i.e. scanny and J.B.) I just increased my pressure (measured cold) from 32 psi to 40 psi for the ride home from work today.

I was pleasantly surprised to see a very noticable improvement in my MPG! No highway driving but I saw a 2 to 2.5 mpg increase from this morning on the same route (45 mph road) which is sweet! I will report back on highway and intend to perform chalk test to evaluate contact area. Personally I feel that 50 or 60 psi for load range C would be overkill.

Has anyone gotten an answer from Goodyear for the load range C DT's for a SR-5 5th gen?

Stu
 
scanny said:
Factory recommended is 32 psi, and by the way 44 is the maximum psi for stock Bridgestones.

I asked Goodyear for recommended Duratracs tires inflation, Goodyear said to inflate according to the load and send me load inflation table for LT tires.
Click to expand...

Can you post the table?
 
JB. said:
If they're the same "size" as the stock P265/70/17 (technically, going to LT qualifies as a size change), the logical starting point is about 44psi which matches the load reserve of the stock tire at door sticker pressure. If the new tire is bigger, that equates to even more load capacity per psi, so, in either case, you have nothing to worry about.

As far as chalk tests, I question the usefullness on an off-road tire. Ultimately, time and wear tell the real story, and higher pressure is much less likely to cause wear problems than lower.
Click to expand...

If the objective is to use the most pressure that still produces a full contact patch (FCP) you want to start where the pressure is just higher then what is needed to produce a FCP. You can then simply release air (instead of having to hook up a compressor) till FCP. If you start from lower pressures and raise it till you reach a FCP, more pressure could be added and still maintain a FCP. You would then have to add pressure till you no longer have a FCP (which is where I recommend to start) and then remove pressure to get max pressure W/FCP. Man, that was a mouthful!

You could also determine the lowest pressure that would achieve a FCP. This could give a starting point to determine how much lower you would need to go for off-road. You would only need to travel a short distance, at low speed using the chalk test.

BTW 265/70/17 is not the stock size.

Also, what does this mean "(technically, going to LT qualifies as a size change)"?

Koz
 
Stu-Runner said:
I am running the C rated 265/70/17 DuraTracs and when I had them installed the tire tech recommended running 32 psi which is what is on the door sticker for the stock bridgestones.

I was somewhat skeptical running the 32 psi and assumed I may need additional psi.

After reading the replies from the guys (i.e. scanny and J.B.) I just increased my pressure (measured cold) from 32 psi to 40 psi for the ride home from work today.

I was pleasantly surprised to see a very noticable improvement in my MPG! No highway driving but I saw a 2 to 2.5 mpg increase from this morning on the same route (45 mph road) which is sweet! I will report back on highway and intend to perform chalk test to evaluate contact area. Personally I feel that 50 or 60 psi for load range C would be overkill.

Has anyone gotten an answer from Goodyear for the load range C DT's for a SR-5 5th gen?

Stu
Click to expand...

Again, I have spent much time experimenting with different pressures on the 4Runner and higher pressures work better in every way (with no adverse negatives).

Koz
 
Koz said:
BTW 265/70/17 is not the stock size.
Koz
Click to expand...

I made the assumption that it is for msommers.

Also, what does this mean "(technically, going to LT qualifies as a size change)"?
Click to expand...

P-metric and LT-metric are sizing systems, which may seem like a trivial detail until you take into account the separate load/inflation curves.
 
Jeremy556 said:
This is probably it:
http://www.goodyear.com/truck/pdf/databook/loadInflation.pdf

Unless I am reading it wrong, for the same load carrying capacity, going from 32psi on (derated) P series 265/70/17 for 2205lb, would be about 44psi on an LT265/70/17, regardless of C,D, or E rating. 45psi gets you 2255lbs on the LTs.
Click to expand...


Correct me if I'm wrong but I don't think we don't have to match stock tire max capacity. This is from manual:

"Check that the number given by dividing the maximum load by 1.10 of
the replacement tire is greater than 1/2 of the Gross Axle Weight Ratings
(GAWR) of either the front axle or the rear axle, whichever is greater.
For the GAWR, see the CertificationLabel. For the maximum load of the
tire, see the load limit at maximum coldtire inflation pressure mentioned on the..."

Rear axle GAWR is 3439 lbs so each tire should support 1719.5 lbs.
As per inflation tables 36psi for stock size can handle bigger load than axle.
And as far as I understand with LT tires there is no need to divide maximum load by 1.10 .
I'm not sure of course that I'm right but so far this is what I figured from manuals, inflation tables etc. As I said please correct me if I'm wrong.
 
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