Wheel weight, old topic -fresh opinions

Donstar · November 13, 2016

I selected p rated Michelins for my truck only because the same sized tire in the LT version weighed 8 lbs. more. I recently read online that such a weight difference wouldn't be noticeable with these new engines. (I have the V6) I cannot readily find the selection but it gave me concern. In your understanding, does tire weight impact gas mileage when choosing between the P or LT versions of the same tire? I have debated the P vs LT question for both sides with the advantage in fuel economy going to the passenger rated version. If this is a myth, then I would love to see it busted!

diyer2 · November 13, 2016

I don't think it's that big of a difference. I always buy LT.

I didn't buy a truck to worry about mileage, if that was the case I would have bought a Prius or Leaf.

SouthernSilveradoGuy85 · November 13, 2016

I don't think it's enough of a difference to worry about until you start lifting the truck 4" or more. Even then the brakes will be effected more. The gas mileage will go down because you're changing the final gear ratio. So lets say you have 3.42, if you lift it and put bigger tires then it will be more like 3.23. Just random to give an idea. That's why people want to regear once you start getting up there on tire size.

If you do a lot of towing and hauling then the LT is a better tire.

Donstar · November 13, 2016

I understand the issues of changing sizes but many tire manufacturers will offer the same sized tire with the same tread pattern in both P and LT rated versions. I was specifically looking at the Michelin Defender and Goodyear Adventurer. I don't haul heavy loads and I know that the LT rated versions of these tires are smooth riding. The difference in purchase price doesn't bother me but it would be unnecessary for me to waste fuel. My concern is that if they both have comparable fuel economy, I would far rather opt for the stronger tire. I am sure others have faced a similar dilemma. I put LT rated tires on my last truck but I also increased size. I don't know how much or if any the weight impacted my mpg.

Grumpy Bear · November 13, 2016

8 lbs. per wheel. 32 pounds of total weight. Thing is tire weight isn't just dead weight. It has an inertia and at the extreme of a 31 inch circle it’s a bunch to start and a bunch to stop. Try running upstairs while carrying four gallons of water.

This is a long debated subject and while there are many to deny weights effect at the wheel/tire, NONE do at the flywheel.

Does a 32 pound difference make a difference at the flywheel on a much smaller circle? Does it matter how far away from the crank it is?

Your question asks if it will have an effect on fuel efficiency. Yes. Will you be able to measure it. That depends on you.

Donstar · November 13, 2016

Your question asks if it will have an effect on fuel efficiency. Yes. Will you be able to measure it. That depends on you.

I am sure there is a measurable difference with the appropriate tests but I guess my question should be "noticeable" difference. Will the numbers I currently see on my DIC be different if I switched to the LT version of my current tire? I imagine carrying a passenger would have a measurable impact on mpg with the right measuring equipment however I've never "noticed" a difference on my DIC. I know that unsprung weight is different so this is an unknown variable. If it was simply a matter of adding 32 lbs. to my truck, I wouldn't give it a second thought!

kstruckcountry · November 13, 2016

I've been running a much more aggressive AT than stock tires for 42,000 miles now. I can't discern a difference, even on long highway trips. I've been tracking MPG since I got the pickup. Heavier tires may hurt some, but many go larger, too. With a larger, heavier tire, you're moving the heavy tread and ply portion of the tire outward, in addition to effectively higher gearing, which is why it's really noticeable then. Given I can still pull down 18.5 mpg on the highway, the most ever on 4 ply was 18.5, I'm happy. I also haven't had a flat in these 42,000 miles, so even if there was a noticeable economy penalty I'd happily pay it.

Another factor is that I have 3.73 gears. Maybe a difference with something like 3.08 would manifest itself?

Sent from my SM-G920V using Tapatalk

Grumpy Bear · November 14, 2016

I am sure there is a measurable difference with the appropriate tests but I guess my question should be "noticeable" difference. Will the numbers I currently see on my DIC be different if I switched to the LT version of my current tire? I imagine carrying a passenger would have a measurable impact on mpg with the right measuring equipment however I've never "noticed" a difference on my DIC. I know that unsprung weight is different so this is an unknown variable. If it was simply a matter of adding 32 lbs. to my truck, I wouldn't give it a second thought!

What would you consider 'noticeable'? E.G. 1 mpg from a base of 20 mpg is 5%. Half that is not only noticeable, it's significant to the engineers that designed your truck to meet a mandated efficiency target. Would be to me as well. Maybe no so much to you? NASCAR teams effect a "noticeable and measureable effect" that wins races with a few feet of duct tape on the grill opening. A half pound of air in a tire. The question isn't about noticeable or measureable its about your perception of what that might be.

I can tell you this however; rotating mass isn't like 'just' carrying a 32 pound medicine ball. It's more like trying catch one thrown at you. The harder its thrown it the more noticeable it becomes. Power by definition is a change of state in energy so yes it makes a difference and the harder you drive the more noticeable it becomes. It being significant to you or even measureable given your instrument and/or ability...well...only you can answer that.

We're you expecting a guaranty? If so I'm sorry to disappoint.

Donstar · November 14, 2016

What would you consider 'noticeable'? E.G. 1 mpg from a base of 20 mpg is 5%. Half that is not only noticeable, it's significant to the engineers that designed your truck to meet a mandated efficiency target. Would be to me as well. Maybe no so much to you? NASCAR teams effect a "noticeable and measureable effect" that wins races with a few feet of duct tape on the grill opening. A half pound of air in a tire. The question isn't about noticeable or measureable its about your perception of what that might be.

I can tell you this however; rotating mass isn't like 'just' carrying a 32 pound medicine ball. It's more like trying catch one thrown at you. The harder its thrown it the more noticeable it becomes. Power by definition is a change of state in energy so yes it makes a difference and the harder you drive the more noticeable it becomes. It being significant to you or even measureable given your instrument and/or ability...well...only you can answer that.

We're you expecting a guaranty? If so I'm sorry to disappoint.

Good response to a difficult question to answer. I don't keep accurate account of my mileage (L/100 km) but I know what to expect my averages on my DIC to look like. The decimal fluctuates but the whole number is pretty constant. I would notice a 0.5 mpg (or metric equivalent) loss and also consider it significant for my current situation. The DIC is fairly sensitive to changes in driving routines. If I notice my average changing, I can usually attribute it to a significant change in activities. If the activity was changing from P to LT tires, then I would consider this noticeable.

Grumpy Bear · November 14, 2016

Good response to a difficult question to answer. I don't keep accurate account of my mileage (L/100 km) but I know what to expect my averages on my DIC to look like. The decimal fluctuates but the whole number is pretty constant. I would notice a 0.5 mpg (or metric equivalent) loss and also consider it significant for my current situation. The DIC is fairly sensitive to changes in driving routines. If I notice my average changing, I can usually attribute it to a significant change in activities. If the activity was changing from P to LT tires, then I would consider this noticeable.

Happy to be of service.