[Update 5] Shop installed the wrong tires.. Need some advice

I run Patagonia MT02's

 

My fault, my reply got partially erased and I didn't notice before submitting it. I meant when you were doing the hard off-roading with 4-ply

 

Curious, how much do you offroad? I ask because those tires are 9lbs lighter, which is a bunch. Your MPG should be a couple/few MPG better. Does that matter to you?

 

The Pat's are the 4PR tires. Before these I wheeled on Treadwright Warden 10PR.

 

I usually get a trip in every 6ish weeks, a bit more frequently than that in the warmer months. While the better MPG would be nice to have, I wouldn't be too bothered if I had to go without it. Most of the spots that I go to are pretty close to where I live

 

oh whoops, I misunderstood. This does make me consider whether I should have a set of off-road wheels/tires and a set of day-to-day wheels/tires. The 4-ply is comfortable but I don't know if I can count on having the kind of luck you had with yours.

 

good advice here. Let us know what you decide.
the 2nd set of wheels/tires for off-roading option is interesting if you don't mind changing back and forth for wheeling....

 

He didn't get C rated, he got SL rated and paid for C. He wanted C rated.

 

As fas as off roading goes, my LT265/75/16 C Load Duratracs were the best tire I owned. Knock on wood, I never got a flat, nor needed an excuse to get a 5th wheel as a spare.

And as a winter tire, they were better on ice/snow compared to my current Wildpeaks.

anywho, my advice go back and demand the tires you paid for.

 

I appreciate the insight. I went up to the shop this afternoon and the owner had stepped out to tend to a family matter, so unfortunately I went up there for nothing. I could have called first but I wanted to bring that up in person to remove any potential for them to come up with any sort of "plan" to avoid making right by the mistake.

I'll update my original post tomorrow afternoon/evening sometime to let everyone know how it goes.

 

I'll make an edit to the original post with an update. I went up there today but the owner had left early for some family matters.

If they were to give me a few hundred bucks back - which is likely still below what it would cost them to correct this - I think I would honestly consider it.. I could pick up some 17" wheels somewhere for the other mud tires they just took off and use those if I were going somewhere where I feel the extra rigidity would be necessary.

Really this is just an unfortunate and annoying situation for everyone. The time it takes to fix, waiting on the tires to arrive etc. and now the additional trips to and from the shop (even stepping away from work to do so).

anyways, I guess that's the fuggin way she goes bud. I'll follow-up tomorrow.

 

It might not be that big of a deal. YEs time lost but if the prioritize your truck they can switch out the tires pretty quick. I've seen Costco do 30 minutes.

I can't see them arguing with you.

 

I hope this is the case. I think the shop was a bit in over their heads with this request. For some reason it took them a full day to get mine done. Dropped off at 0900 and picked up at 1800. It's been a shit show so far so we'll see if my luck turns around tomorrow.

Also maybe I should have just gone to Costco.. lmao

 

I have a thread talking about my Costco experience. Long story short, they won't install tires 3% bigger than your stock size listed on the door jam. Not sure if this goes for all Costcos, but the one I went to checked and refused to install the tires I ordered. Second Costco I went to (I ordered stock size) didn't even look at door jam.

 

Its a counter intuitive, but for example if we take stock tacoma PSI (29 PSI), the E load tire will need more PSI to support the same weight as a P metric tire.

I ran about 35-37 PSI on my E load KO2s when my truck was stock. Right now Im running 40-42 PSI on my E rated Wildpeaks due to added weight.

Just check out this tire pressure calculator and see for yourself:
https://www.google.com/url?sa=t&sou...IQFnoECBUQAQ&usg=AOvVaw104gHW1RNrVtENucjBoGTV

 

thanks for the link. I punched everything in and it appears that the shop was completely convinced these were the LT tires that they put on... They inflated them to 35 PSI, though the ones I actually have call for 27 PSI. Not sure if that's large enough of a surplus to cause any damage to a new set of tires, but with my luck throughout this whole thing I'm not sure I'd rule it out

 

I'm not sure you understand the physics. Tires are not supported by the rubber. They are supported by the volume of air in the tire. You don't add air pressure because you change a tires ability to hold more. Air pressure isn't as simple as an online calculator. There are so many factors that it is impossible to create an ideal pressure for everyone. When it comes to pressure, you never want to go lower than the placard and you never want to go above the cold psi on the sidewall of the tires. Even with that as the generally accepted rules, you can still go over or under depending on your circumstance.

For the OP, Nitto is stating that tires that can have more air actually carry less weight. That makes zero sense. If you look at their other tires, all of the higher load indexes all carry heavier loads. Ridge Grappler | Hybrid Terrain Light Truck Tire | Nitto Tire

 

I would seriously doubt they took anything into consideration regarding the air pressure you left with. Pretty much every truck will leave with 35ps. The tires don't call for a specific PSI. There is only a maximum and it sounds like the tires you got have a maximum of 44 psi. Your placard probably shows 30psi. And no, that pressure will have any impact on the condition of your tires whatsoever. Please don't even bring that up because you will lose any credibility to your argument. If someone were to point that out to me, I would immediately know that the person has little tire knowledge.

 

There are 6 different types of tire construction, and the pressure affects each differently. An LT rated tire definitely needs more air than its same size SL counterpart. It is absolutely as simple as using a calculator, calculating what the stock tire was capable of at the recommended pressure.

An SL rated tire does carry more weight than an LT at lower pressure...until a certain point when the SL maxes out around 35-45 psi while the C load LT goes to 50, D load LT goes to 65, and E LT load goes to 80.

An LT needs more air pressure in the tire because it is a stiffer construction and the extra pressure helps keep the tire in the shape it needs to be in. How much air it takes to make that happen depends on how much load the vehicle applies to the tire, hence why you use the door placard pressure to run a calculation to see where the new tire needs to be.

The door placard is not useful at all once you know the stock design carrying capacity. There are absolutely cases where the stock tire pressure is too high for a new larger tire you may choose. It's exactly why the door placard is different for each trim, because they all have different wheels and tires, changing where the pressure needs to be to carry the load.

So... yes, tires can have "more air" carry less weight, if the tire design needs more help in the form of air pressure to maintain its shape.

 

Several things:

The Nitto Ridge Grappler 285/70R17 comes in 3 versions:

285/70R17 SL 116Q - 2,756 lb capacity max @ 44 psi (lowest capacity starts at 22 psi) - 48 lbs
LT285/70R17 C 116/113Q - 2,755 lb capacity max @ 50 psi (lowest capacity starts at 35 psi) - 55 lbs
LT285/70R17 E 121/118Q - 3,195 lb capacity max @ 80 psi (lowest capacity starts at 35 psi) - also 55 lbs

There is probably some slight error in the weights, I bet the E load is actually more like 60 lbs. But anyways.

First, none of those tires listed above are p-metric. Nothing is P-metric unless it has a P in the front. The first one is a euro-metric or just metric.

The SL tire will absolutely carry its ideal weight at less than stock pressure because the stock tire is an SL and any larger tire in the same type of construction always carries the same weight capacity at less pressure comparatively due to the larger volume of air in a larger tire. So you drop the pressure.

Stock TRD Off-Road:

265/70R16 112T @ 30 PSI - carries 2122 lbs at that pressure in stock form, which is what we need to compare the others to.

Comparisons:

SL:

285/70R17 116Q - carries 2177 lbs @ 27 psi....so on that tire, 27 psi is correct.

SL tires contain a 10% weight overage in them, which LTs do not use. So to calculate where LTs should be, we remove that. So the new stock weight capacity is 1,929 lbs.

LTs:

LT285/70R17 116/113Q - not rated below 35 psi, and it carries 2,105 lbs at 35 psi, so technically we are already over inflated at 35 psi.
LT285/70R17 121/118Q - not rated below 35 psi, and it carries 2,105 lbs at 35 psi, so technically once again we are already over inflated for the truck at the minimum pressure rating of an LT285/70R17.

LTs of all load ratings (C, D, E, etc) all start at the same minimum pressure rating, and climb the same. What changes is the D and E continue to climb beyond the C's max. Then at 65 psi (D's max), the E continues to climb until it's max at 80. They all need the same pressure to carry the same load.



So:

This is backwards. The SLs are lighter as I pointed out in the weight listings. The extra 3/32 tread is on the LT models, not the SLs. The LTs (both C and E) are heavier. The metrics do have a 1 lb higher rating at their max pressure than the C load counterpart but... the C loads will still be a stronger tire. You have to consider the 10% overage on an SL tire (so really the carrying capacity of an SL on a truck would be 270 lbs less), and the C's will have stronger sidewalls. It's just that they don't have strong enough sidewalls for their max load to keep on climbing. But the C is a stronger tire overall than an SL.

The E and C are mostly the same except the E has a stronger sidewall and will support more load than any of them at its max, 80 psi.

The plies are rated in equivalents, yes. Doesn't really matter how many actual layers there are as long as they do what they are supposed to do. Despite carrying more weight at a lower required pressure, the SL always will have weaker sidewalls. Whether it's less actual plies, or the same number of plies but thinner, they will always be weaker. That is why they (SLs) bulge so much to carry a load. The reason they "carry" more weight at less pressure is because they are easier to inflate and seat to the rim, unlike an LT which is stiff and needs more air to do that properly. The bulge from lower pressure also creates more contact with the ground which helps the SLs have better traction.

Typically, the ply rating equivalents are as follows:

SL - 4 ply
B load LT - 4 ply
C load LT - 6 ply
D load LT - 8 ply
E load LT - 10 ply