Whatever the topic , this is what happens here . Most days I'm just here for the entertainment .All this over tire pressure? Imagine if these guys took flying lessons!
Whatever the topic , this is what happens here . Most days I'm just here for the entertainment .All this over tire pressure? Imagine if these guys took flying lessons!
I run 10 ply tires because I use my truck AS a truck. I haul things...sometimes heavy things. I pull trailers...sometimes heavy trailers. I go offroad fairly often. I have even drag raced it. But it's still my daily driver. I run 285/75's because of added ground clearance...I also have a 3" leveling kit. 285/75's are next to impossible to find that AREN'T E-rated.Curious as to your reason for using a load-range E tire on a 1/2 ton?
Dangerously underinflated in terms of the load carrying capacity, as has already been discussed. You can see this just using the numbers I've already posted, by running below 45psi, you have a tire that has a lower load carrying capacity than the truck was shipped with. @CapriRacer has said the same. That doesn't mean the tire is going to sit funny or wear oddly, it simply means it isn't rated to be able to safely handle the same load at that pressure.
I mean, I use my truck as a truck too, but still run P-rated tires, because their limits align with the limits of the truck The statement that one needs LT tires to use a truck "as a truck" is like the personification of "truck nuts". The fact that many guys doing it aren't running proper air pressure because they aren't aware of the existence of the load tables is just the icing on the cake. I think we can avoid taking this conversation down that road.I run 10 ply tires because I use my truck AS a truck. I haul things...sometimes heavy things. I pull trailers...sometimes heavy trailers. I go offroad fairly often. I have even drag raced it. But it's still my daily driver. I run 285/75's because of added ground clearance...I also have a 3" leveling kit. 285/75's are next to impossible to find that AREN'T E-rated.
But you aren't "supposed to" on a 1/2 ton, that's why the placard doesn't contain entries for loaded/unloaded. On a 3/4 or 1-ton, they'll often give multiple pressures on the placard for loaded/unloaded, my old F-250 did. However, these come with LT tires on them factory and the placard directly applies, while 1/2 tons don't, which is why one is required to derive the appropriate pressure from the load tables as indicated. For your truck, 45psi is appropriate for the stock load carrying capacity of the vehicle, assuming the numbers I used to derive that were correct, based on the sizes given.When I haul a heavy load, I bump up the inflation to a pressure suitable to the load...like you're supposed to do.
Again, the loads your truck is rated to carry are well within the limits of the stock tires, a 1/2 ton doesn't need an E-rated tire to "handle" a load and as already discussed, needs higher pressure in order to handle the same load; have the same load carrying capacity.When I'm not hauling anything, I run them @ 35psi. I don't haul loads often enough to warrant having to buy a bigger truck, but often enough to warrant a tire that will handle it...
Yes, they typically employ a harder compound, due to their intended application and operating profile, and subsequently have longer tread life. The downside of course is that, at the proper pressure, they provide a poorer ride that some may object to.plus I like the mpg I'm getting with mine. I'm right at 20mpg on the hwy. Also, the 10 ply tires last longer in an apples to apples use comparison for what I'm doing vs a SL, C or D rated tire.
Yeah, my truck isn't "supposed" to run over 99mph, but it does. My truck isn't "supposed" to haul a 1 ton load in the bed, but it does. My truck isn't supposed to tow over 5000lbs, but it does. You aren't supposed to use a screw driver as a prying tool or chisel...but people do it all the time. Pushing my truck past what it's engineered limits supposedly are certainly have never hurt it, or me, or anybody else.I mean, I use my truck as a truck too, but still run P-rated tires, because their limits align with the limits of the truck The statement that one needs LT tires to use a truck "as a truck" is like the personification of "truck nuts". The fact that many guys doing it aren't running proper air pressure because they aren't aware of the existence of the load tables is just the icing on the cake. I think we can avoid taking this conversation down that road.
And yes, the size you've chosen does limit you to LT tires, though I do see one that isn't E rated (Toyo Open Country A/T III), but most seem to be.
But you aren't "supposed to" on a 1/2 ton, that's why the placard doesn't contain entries for loaded/unloaded. On a 3/4 or 1-ton, they'll often give multiple pressures on the placard for loaded/unloaded, my old F-250 did. However, these come with LT tires on them factory and the placard directly applies, while 1/2 tons don't, which is why one is required to derive the appropriate pressure from the load tables as indicated. For your truck, 45psi is appropriate for the stock load carrying capacity of the vehicle, assuming the numbers I used to derive that were correct, based on the sizes given.
Again, the loads your truck is rated to carry are well within the limits of the stock tires, a 1/2 ton doesn't need an E-rated tire to "handle" a load and as already discussed, needs higher pressure in order to handle the same load; have the same load carrying capacity.
Yes, they typically employ a harder compound, due to their intended application and operating profile, and subsequently have longer tread life. The downside of course is that, at the proper pressure, they provide a poorer ride that some may object to.
It's probably the most common tire "swap" in North America, the fitment of LT's to 1/2 tons that spec P-Metric. I've got no issue with it, heck, our Expedition came with LT's on it when we bought it (it spec'd P-Metric) and I went down the rabbit hole of having to determine the appropriate pressure after learning from @CapriRacer's data that running them at placard was wrong. However, most people doing it aren't doing it correctly. Tire pressure is one of the most misunderstood and hotly contested subjects on this forum!
I'm also curious why you didn't mention that you "adjusted" your pressure in any of your previous responses? Clearly, that's germane to this discussion One would have assumed you'd bring this up right out of the gate, given the context of the discourse thus far and the fact that these last few responses have specifically referenced pressure on LT tires needing to be higher than a comparable P-Metric in order to have the same load carrying capacity.
The tires aren't the weak link in over-loading a truck (which you are admitting to doing here). The frame, brakes, axles, and other components are simply not designed to handle that kind of weight, that's why they make bigger trucks, with heavier components in all of those departments.Yeah, my truck isn't "supposed" to run over 99mph, but it does. My truck isn't "supposed" to haul a 1 ton load in the bed, but it does. My truck isn't supposed to tow over 5000lbs, but it does. You aren't supposed to use a screw driver as a prying tool or chisel...but people do it all the time. Pushing my truck past what it's engineered limits supposedly are certainly have never hurt it, or me, or anybody else.
I also had awful luck with the factory tires on our RAM (Goodyear Eagle). They lasted about 40,000Km and were close to bald. The pictures are on here. We replaced them with Conti's, was going to go LTX's, as I've had fantastic service out of those on other vehicles, but the price break on the Conti's made the gamble worthwhile. Can't comment on wear yet, but they seem to do well in other important metrics like wet performance, stability while towing...etc.Plain and simple, the factory P-metric Firestone tires that were on my truck from the factory lasted about 20K miles. I thought it must have been just bad quality tires. So I put on the same factory spec tire in a Michelin AT (the best of the best, right?). They too lasted ~20K miles.
Again, it's not about wear or likely anything visible, the tire simply isn't rated to carry the same weight at 35psi as the stock tires. How close you are coming to the "lower than factory" limit you've created during daily operation? I don't know, would depend on what you regularly have in the vehicle, but the fact is that it's lower than the OE tires at the same pressure and that's why it was brought up.Moved up to D rated when I lifted the truck and went with the bigger tire. Got ~40K miles out of those. The trend seemed obvious. So...I went with the E-rated....been getting consistent 65-75k miles out of them ever since. Never seen any evidence of a safety issue or premature wear or any type of failure running them @ 35 psi. On my truck, they ride better, they handle better, wear better AND they last longer at that pressure.
No, not with 1/2 ton trucks, that have a single pressure spec on the placard, and this thread, and most of the discussion, revolves around placard pressure and its appropriateness, including the posts you've been responding to, that's why I don't get it. There was a clear segue into this conversation in mentioning it, but instead, you just sarcastically quoted Michelin and completely avoided it, that's why I made it a point to break that out specifically as an item of interest.Why didn't I mention adjusting air pressure when hauling heavy stuff? Well I guess since I'm a truck driver who deals with heavy loads and logistics, I assumed it was common knowledge that it's people adjust air to accommodate heavy loads. I guess it's not?
Again, back to the subject, an E-rated tire at 35psi does not have the same load carrying capacity as the factory P-Metric ones and typically the placard isn't updated with the correct pressure when an LT is fitted to a P-Metric application. This creates a hazard if the owner isn't cognizant of the fact that the placard pressure is no longer correct and in order to use the vehicle safely within its limits, they will need to significantly increase that pressure beyond what is on the placard, using the load tables.My question to YOU is...why does it matter to you if I run E-rated tires @ 35 psi on my 1/2 ton truck on a normal basis? It's not a danger to anybody...not me as an operator and not anybody else on the road.
Yes it is- because when you have a tire failure and lose control, you risk the lives of others around you.It's not a danger to anybody...not me as an operator and not anybody else on the road.
Except your approach is clearly incorrect. Multiple posters have proven this using industry-standard reference materials and guidelines. Just because someone is experienced in their area does not mean their experience is valid and correct.I'll be abundantly clear then, too. You do you...and I'll do me...and every body lives in harmony.
Don't bet on it.Golddot immediately went out and bumped his load range E tires up to 45 psi after reading the exchange. We’ve all learned new things on the internet.
A tire failure? Explain how from an engineering standpoint it would cause a tire failure.Yes it is- because when you have a tire failure and lose control, you risk the lives of others around you.
Except your approach is clearly incorrect. Multiple posters have proven this using industry-standard reference materials and guidelines. Just because someone is experienced in their area does not mean their experience is valid and correct.
Underinflation increases the risk of tire failure.A tire failure? Explain how from an engineering standpoint it would cause a tire failure.
Something I've been doing for 25 years with this truck and others I've owned...that has never caused an issue for me or anybody around me is "incorrect"? A man isn't "just lucky" for 25 years. I have well over 200K miles of uneventful use on E-rated tires running them @35 psi. It's not hurting-a-thing. Those "industry standards" is not an exact science nor is it a once size fits all. It is simply a recommendation.
Then first about the loadindex of the 285/75R17. 121/118Sure, but we aren't talking about cars, we are talking about trucks, which is where this whole charade with respect to the fitment of LT tires and improper inflation becomes the issue.
This is the example tire I used, it is indeed Load Range E:
View attachment 90755
For the RAM 1500? It's in that chart I linked you, 3,700lbs.
The point being, if buddy with the LT's has a 4,100lb GAWR for the rear axle, like my RAM, and he's running 35psi, he's got a load carrying capacity of 3,780lbs for the tires. The tires aren't suitable/safe at that pressure to carry the load the truck is rated for.
@CapriRacer noted earlier in the thread that LI for Euro tires is a bit different than for American ones:Then first about the loadindex of the 285/75R17. 121/118
Its stangely low.
A 225/75R16 tire in LT has 115 AT 80 psi loadindex.
European C-tyre in same sise LI 118 AT 77psi and LI 121 AT 83 psi.
Seached with google, but only saw LT.
I think in Europe the 285/75R17 is not an interesting sise in C-tire, did not even found it in normal car or XL tyre.
So a smaller tire but same loadindex.
So I expect a 285 , if it was available in Europa , it would have a higher loadindex AT 80 psi ( or 77 or 83psi).
285-225 = 6 x10 + 1 step for 17" against 16" gives aloadindex of 121+7= 128.
LT 115 +7= 122, so that is pretty much in line with the 121 given for 285.
Perhaps it is time for a bit of a lesson in Tire Engineering:
A P225/50R17 has a load carrying capacity of 1433# @ 35 psi. LI = 93 This would be the US tire standard as published by The Tire and Rim Association.
For the European tire standard, a 225/50R17 has a Load Index of 94 - and you'd think that's different, but LI=94 means the load carrying capacity is 670kg @ 250 kPa or 1477# @ 36.3 psi. If you do the math, those are very close to the same.
As noted though, these are indeed LI121, which is 3,195lbs @ 80psi.New calculations:
Front GAWR 3700lbs +10% reserve=4070.lbs.
LI 121 / 3200lbsx2tires= 6400lbs.
LI 128/ 3970lbs x 2 tires= 7940lbs.
(4070lbs/6400lb)^1,25 x 80psi= 45.43psi ,
Make it 45 or 46 psi front.
But if 128LI
(4070lbs/7940lbs)^1.25 x 80psi= 34.69 psi , make it 35 psi.
So the one that used 35psi all around for almost empty driving, probably did not destoy his ( or her) tires by it.
Because empty driving weigt on rear axle is about the same or lower as front axle.
Yes, as I noted above, it appears LI is different as well, according to CapriRacer.All general , RV and towing is a different story. no overheating depends on laws of mother nature, wich not always follows the rules and systems the ( tire) organisations agreed on , and EUR and USA system not always agree with each other.
EDIT
Yes, now base weight will be a bit variable here. My truck on that table has the following specs:Looked back the topic and saw the list you gave . Not only GAWR's are given there , but also base weigh, and comfirms my only driver axleloads of front about 3000 lbs and rear about 2200 lbs. So the 99% normal driving most do ( no towing , RV , transporting heavy loads or many persons) next pressures for that
Front 3200lbs+10% = 3520 lbs .
Rear 2400lbs + 10%= 2640 lbs
Only the 120LI AT 80 psi.
Front (3520lbs/ 6400lbs)^1.25 x 80 psi = 37.89psi rounded 38psi.
Rear ( 2640lbs=6400lbs)^1.25 x80psi= 26.44psi, rounded 27 psi, make it 30 psi.
And this is for max speed 99mph, for lower speed lower pressure would not give overheating.
So still for most normal used 35psi will still not give overheating.
Again : determining the weights in your use , stays the most tricky part in this.
A tire engineer explained it. Twice.Still waiting for somebody to explain...from an engineering view...why they think my E rated tires are under inflated WITHOUT a chart saying so. I will remind you folks that I drive for a living. I am approaching 2 million incident/accident free miles in an 18 wheeler alone...not counting my personal vehicles. I know a thing or 3 about tires.
Under inflated tires cause more sidewall flex and extra friction within the tread contact which creates excessive heat in the tire...that excess heat is what starts breaking down the tire's construction and results in a blowout. (ANYBODY CARE TO DISPUTE THAT?) My tires have near sidewall zero bulge or distortion.
Passenger vehicle and truck tires typically are good up to 195°F before the tread compound begins to deteriorate rapidly. Into the 225-250°F range is when they structurally begin to disintegrate....regardless of their temperature rating.
I've gauaged my tires with my infrared thermometer on a 95°F (ambient) temp day during a 160 mile trip running 65-70 mph. All 4 tires were 160-162°F with the asphalt right around 155°F. They run way cooler on cooler days. Using that as a rule, I'm well within the safe zone with my tire pressure.
My daughter was following me in her car with the factory size and spec tire running the pressure on her door placard which is 35 psi. Her tires were 5° warmer than mine. I assume the difference is because my 33" tall tire is turning way less revolutions than her 25.7" tire in the same distance.
So...let's hear why I'm wrong with my tire pressure again?