P metric -vs LT tires - ride quality, MPG, etc.?

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I'm a little surprised by the MPG loss reports-harder rubber, less sidewall flexing, less rubber on the road (with any load at all) should mean less heat & less fuel consumption. Unless we're comparing mud tires to all-season P metric, I'm not getting it.

In my case that I referenced, the LT tire I choose is a somewhat mild tread A/T, and 12 lbs heavier than the OEM all-season P-metric. The difference in weight is definitely a factor.

The new tires are vastly better in the wet, snow, and 4wd trails. Obviously they'd be lacking in deep mud. But in some moderate mud they did fine. On-road they are nearly as quiet as the OEM tires. They're just a better all-around tire for an SUV that doesn't see only dry pavement.

The OEM tires: https://www.tirerack.com/tires/tire...ewall=Blackwall&partnum=67SR7AT20V2&tab=Sizes

The tires that replaced the OEM tires: https://www.tirerack.com/tires/tires.jsp?tireMake=Yokohama&tireModel=Geolandar+A/T+G015&sidewall=Outlined White Letters&partnum=67SR7G015OWLV2&tab=Sizes
 
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I'm a little surprised by the MPG loss reports-harder rubber, less sidewall flexing, less rubber on the road (with any load at all) should mean less heat & less fuel consumption. Unless we're comparing mud tires to all-season P metric, I'm not getting it.
It's the increased weight/rotational mass of the LT tire thats causes the mpg drop. Once you're rolling with no elevation/grade change, its minimal. In everyday stop and go traffic, accelerating, and elevation/grade changes, it can be easily be 2+mpg loss. On the more common tires sizes of 31"-33" tires that light duty trucks/suv have, its 15-20 lbs per tire difference depending on what load range the tire is (C,D,E). For 4 tires, you're looking at 60-80lbs increased rotational mass.
 
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I'm happy with the switch from P-metric to LT on my avalanche. Much more stable towing. At low speed bumps are a touch harsher. But nothing that bothers me. As far as mpg, i don't measure it, its a truck, it only got 13 city 18 hwy with the p metrics. I don't think is worse with the LT. Maybe if i was driving city stop and go. but towing hwy , i don't see much difference.
 
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Never heard of a TPMS system that alerts the driver of too high air pressure, just when the pressure drop below the acceptable threshold (direct sensor) or if the rotation rate deviates significantly between tires (indirect monitoring).
Two of my cars will set off TPMS when pressure is too high. 07 Chevy and 11 Kia. It's a real PIA if you choose to run higher pressures than OEM recommendation.
I don't know what protocols Toyota uses.
 
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Static load and dynamic loading of tires are two different things.
Let's say that the GVW of your vehicle is 8,000 lbs. The vehicle is loaded so that there's 2,000 lbs on each tire, and the tires are rated at 2,000 lbs.
Step on the gas and weight transfers to the rear. Now the back tires are overloaded. Step on the brakes and weight is transferred to the front.
Brake going downhill on a right hand curve; more weight is transferred to the front left tire than the other three. Climbing a hill on a right hand curve? The back right tire is doing all the work driving the vehicle (2wd), with increased weight applied.
Air pressure keeps tires from peeling off the wheels, especially important downhill braking on a curve.
 
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It's the increased weight/rotational mass of the LT tire thats causes the mpg drop. Once you're rolling with no elevation/grade change, its minimal. In everyday stop and go traffic, accelerating, and elevation/grade changes, it can be easily be 2+mpg loss. On the more common tires sizes of 31"-33" tires that light duty trucks/suv have, its 15-20 lbs per tire difference depending on what load range the tire is (C,D,E). For 4 tires, you're looking at 60-80lbs increased rotational mass.
Ahhhh ..... Mmmmm ...... Not exactly.

While it is true that the increased mass of LT tires (which is mostly more tread rubber) does contribute to less fuel economy, the rubber itself is less fuel-friendly. In the process of making the rubber more capable of handling the higher loads, the rubber chemists are forced to make some changes that increase the hysteresis (the difference between the amount of energy put in to bend the rubber vs how much energy comes back out.) Hysteresis IS rolling resistance. This is in spite of the increased inflation pressure for the same load.
 
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tyres being unsprung weigh are very important + beside the already mentioned heavier tyres as well as wheels wear bearings etc faster. for load ratings be sure to multiply by 4. on my 2011 fronty SV i went from OE 265-70-16 to 245-75-16 lighter + cheeper + still plenty of capacity to haul legal 1/2 ton of coal or even 3/4 ton. i always check diameters as well + my swap was almost the same. a cheep way to change gear ratios.
 
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tyres being unsprung weigh are very important + beside the already mentioned heavier tyres as well as wheels wear bearings etc faster. for load ratings be sure to multiply by 4. on my 2011 fronty SV i went from OE 265-70-16 to 245-75-16 lighter + cheeper + still plenty of capacity to haul legal 1/2 ton of coal or even 3/4 ton. i always check diameters as well + my swap was almost the same. a cheep way to change gear ratios.
I did the same with a 2013 GMC 1500. Went from 275/55/20 on a 20x8.5" wheel to 265/60/20 LT-E, take-offs from my 2011 2500.
The 2500 got 275/65/20s on the stock 20x8.5 wheels, another winter set Hankook RW-11 studded on 20x9" wheels and lastly
295/65/20 Toyo CTs on 20x10 Fuel Cyclone wheels.
My daughter's 3500 Chev got 285/75/18s on the stock wheels and the 265/70/18s were sent down to the 1500 on a set of 18x9" wheels.

I think that the fuel economy hit guys report are in part from putting bigger tires on the stock wheels.
You went the other way and eliminated some sidewall flex, which generates heat, wear the tires faster and hurts fuel economy.

Edit; I'm looking at buying a GMC Acadia AT4. The stock SL tires will go on CL and 245/70/17 Toyo CTs on the SUV.
 
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tyres being unsprung weigh are very important + beside the already mentioned heavier tyres as well as wheels wear bearings etc faster. for load ratings be sure to multiply by 4. on my 2011 fronty SV i went from OE 265-70-16 to 245-75-16 lighter + cheeper + still plenty of capacity to haul legal 1/2 ton of coal or even 3/4 ton. i always check diameters as well + my swap was almost the same. a cheep way to change gear ratios.
Fronty?

oh lord

please don't ever refer to it like that again lmao
 
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