Pirelli Scorpion ATR LT265/75R16 on my new Navara

[T.Low]

suprised in snow and ice

It's done. I handed over $850 for a five-piece set of Pirelli Scorpion ATR LT265/75R16 on my new Navara. I've got them at 50psi, and could not feel any appreciable increase in noise or roughness. Granted I only rode about 300km on the stock tires (Dunlop Grandtrek 255/70 AT20) so I did not sufficiently get accustomed to them. I think I got just a bit less than one inch in lift. Those LT Scorpions should be able to tackle anything (except mud) that Indonesia can dish out.

I have a set on my company truck. I could not believe how well they handled in snow and icey hills, just in case you get some snow any time soon with all this climate change.

 

[mauricio_28]

There is snow in Indonesia, the glaciers of Papua's highest peaks, but the rest of the country is balmy tropical. Seriously though, so far so good with the tires. I am not experiencing the ills associated with over-inflatation, though it's much too early to tell uneven wear. I may air down a bit, but unless someone can refute tire manufacturers' guidance regarding increased pressure for LT tires, I am staying in the 40-45psi range. Glad to hear about their bite in "soft" conditions. They probably aren't user-rated no.1 at the Tire Rack for nothin'.

MADIZELL, why in your opionion did Nissan chose 35psi as the stock pressure, front and rear, for the Frontier/Navara? Also, that Toyo link that you provided confirms what I've been saying all along. In the example of the change from a P to an LT tire in Toyo's document, the pressure in the former was 35psi while in the latter 45psi. Meaning, for the same load the LT tire requires more air pressure. Moreover, immediately after the example the document states:

"...size for size, LT-metric tires require higher air pressures to carry equivalent loads of P-metric tires...due to the higher PSI requirements of LT-Metric tires..."

 

[madizell]

There is snow in Indonesia, the glaciers of Papua's highest peaks, but the rest of the country is balmy tropical. Seriously though, so far so good with the tires. I am not experiencing the ills associated with over-inflatation, though it's much too early to tell uneven wear. I may air down a bit, but unless someone can refute tire manufacturers' guidance regarding increased pressure for LT tires, I am staying in the 40-45psi range. Glad to hear about their bite in "soft" conditions. They probably aren't user-rated no.1 at the Tire Rack for nothin'.

MADIZELL, why in your opionion did Nissan chose 35psi as the stock pressure, front and rear, for the Frontier/Navara? Also, that Toyo link that you provided confirms what I've been saying all along. In the example of the change from a P to an LT tire in Toyo's document, the pressure in the former was 35psi while in the latter 45psi. Meaning, for the same load the LT tire requires more air pressure. Moreover, immediately after the example the document states:

"...size for size, LT-metric tires require higher air pressures to carry equivalent loads of P-metric tires...due to the higher PSI requirements of LT-Metric tires..."

Statements in the general regarding relatively higher pressures for once style of tire versus another are just that -- generalities. And, actually the statements you are seeing are intended to be read in the obverse. That is, for a given pressure, an LT tire has to be down-graded about 9% in load capacity versus the P-metric. Thus, stated the other way around, if you want to carry the same weight with an LT, you have to increase pressure by a factor of 1.1. Even in your example, if the vehicle can carry 2,000 pounds more than the GVWR without exceeding the load capacity of the tire at 35psi, you can deflate to a lower pressure than 35psi and still carry the GVWR. If you can carry the weight with a P-metric at not more than 35, then all other things being equal, you would still never need to inflate a similar LT by more than 1.1 times 35psi, which is 38.5 pounds, stating it your way around. 35 or 38.5, whatever, it still is not 45 or 50psi, which is far and away too much air for the tire mounted on your vehicle. Mount the same tire on an F-350 and the answer could be different.

The Toyo line item numbers for an LT 265/75/16 are tire specific for loads and pressures, not generalities. These are engineer tested capacities which Toyo is willing to stand behind, or they would never have published them. Whether those numbers are higher or lower than a P-metric tire of the same size is a factoid of no relevance when empirical data regarding actual pressure needed to carry actual load with an actual class of tire is provided.

As for your other question, with the change to TPMS requirements, and with a regulatory range of inflations limited to placard pressure to 25% below placard pressure as the mandatory range within which the TPMS sensor MUST trigger a fault, and with only a small range of products available from which to choose, and with these identical systems to be installed on a broad class of similar but different build levels of trucks and cars, Nissan made a conservative choice in the Schrader product for the Frontier using a trigger target of 31-32psi. Trigger pressures of 31.5psi are only 9 percent below the placard of 35psi, and since Nissan could have gone to 25%, or 26.5psi, as a trigger point, I would say choosing 31.5spi or 9 percent was conservative. Given the range of tires for which the truck was designed, it is a given that no more than about 32 to 35 pounds of air would be needed to carry the GVWR no matter whose tires you mount, so a TPMS sensor was chosen that was about the next one lower than the maximum needed pressure.

Then to, because there is now a sensor on board which has a very narrow range of usable pressures without exceeding the placard, and because Nissan does not want to talk about this repeatedly with every customer from now on, Nissan and all other manufacturers are now stating only ONE pressure per TPMS-equipped vehicle. That pressure is necessarily the highest necessary pressure, not an intermediate one, again out of an abundance of caution, because if you can state only one pressure (so as to avoid variables), which one would you choose? There is only a 9 percent margin for error to start with given the equipment Nissan chose to use. Why make it less by stating an acceptable range of, say 33 to 35, knowing that the first time you lower the pressure to 33psi and the temperature drops overnight, the TPMS will trigger a fault. Customer complaints would never stop. So, the good folks at Nissan, having decided to use a 31.5psi trigger, state only the top-most pressure and let it go at that. That this will increase tire wear-out and impact the handling of the vehicle is of no matter, because that is the lesser of two evils when faced with the US government declaring mandatory if stupid on board systems for new cars and trucks.

Read the white papers provided by quite a few of the manufacturers, including Nissan and Toyota, to the government during the drafting of the regulations. Why they are now doing what they are doing becomes clear, and the problem of constant customer complaints was timely raised, addressed, and then left to the auto makers to deal with.

 

[mauricio_28]

I tested the contact patch by driving over a sheet of white paper. 50psi was indeed too high, particularly for the rear. I'll see how they ride now at 40psi rear/45psi front.
BTW, the weight distribution of my stock Navara (Crew Cab, diesel engine) is 1160kg front/800kg rear, a 59%/41% distribution.

 

[madizell]

I assumed it might be around 60/40 f/r. Most pickups are front-biased. Keep experimenting with pressures until you are happy with the result. If you want to get really picky, keep in mind that pressure in front tires might not be equal to rear due to different weight. Lots of cars and truck used to have different front and rear pressures stated on the placard where now they usually have but one. Physics hasn't changed, only the politics of the moment.

 

[mauricio_28]

I am coming around to the idea that, despite tire manufacturers' advice and my initial resistance to MADIZELL's advice, the proper pressure, unloaded, is somewhere around 40psi front/ 35psi rear. In retrospect now that I've aired down, 50psi felt like, for those of you who mountain bike, exactly like 50psi feels on a rocky trail, bouncy.

 

[Redline]

I just scanned this thread, but from what I read I'm in total agreement with Madizell. Appropriate PSI for the load is the goal.

Proper psi will yield better ride, traction, and wear.

They tell you to inflate them 'high' for the maximum load the vehicle/tires are rated to carry, not what you are actually loaded with at the moment. If you want better ride, traction, and wear you need to experiment.

I am coming around to the idea that, despite tire manufacturers' advice and my initial resistance to MADIZELL's advice, the proper pressure, unloaded, is somewhere around 40psi front/ 35psi rear. In retrospect now that I've aired down, 50psi felt like, for those of you who mountain bike, exactly like 50psi feels on a rocky trail, bouncy.

 

[mauricio_28]

Here, finally, is a shot of the Scorpions:

 

[madizell]

That's actually a sharp looking tire. Let us know how it wears, and if you get the chance, how it works in the dirt.

 

[mauricio_28]

After nine months and about 13,000 km, the Scorpions are wearing well and evenly. They've only let me down in mud and sand. No problems so far, not even a flat, after a 6,600 km expedition through eastern Indonesia.

The next tire purchase is a set of Toyo Open Country MTs