10 lbs, per tire lighter and no better MPG,,wtf..

The net torque required to rotate an object at a constant rate is zero. I tried to calculate the force required to accelerate it but either my math is wrong, I'm using the wrong formula or this is somehow correct. Given some basic assumptions, accelerate a 30", 40lb cylinder to 60mph (11.2 ft/s) (rotational speed) in 10 seconds, I calculated the required torque to be 0.114 ft/lbs.

 

i dont have a lead foot, same driving habits, just thought it would make a differance,, there i go thinking ,,lol

 

We seem to be forgetting rolling resistance, some tires are plain and simple harder to roll across the tarmac with a truck on them. Same tire in a different load rating could have significantly higher rolling resistance. All how it rolls from one radial ply to the next, in milli seconds at speed.... Really.

 

I had the stock 16" OR wheels and changed over to the 17" SEMA wheel and 265/75r17 Grabber ATX. Was seeing around 21 mpg on the highway and am now seeing around 19 mpg. Around town didn't change too much it seems. Was a little bummed about it at first but the happiness I feel when looking at my truck now versus with the stock setup, is worth it. Was surprised in this change but doesn't bother me too much.

 

I've seen dynp runs where a lighter set of tires on aluminum rims was swapped for a heavier set of tires on steel rims. The dyno read less HP and Torque with the heavier rims and tires. l think the weigh difference was about 20 - 25 lbs per wheel. If I remember correctly, it was a Chevy Yukon. Different vehicle but the premise shoud be the same.

 

There are a lot of factors involved some with tires such as- yes the weight but also tread, compound, diameter and one that might not have been considered is aerodynamics. The frontal area is what compared to stock tire size? It could also be a gearing issue.

 

Is it possibly colder than it was before? Temperature has a large effect on fuel economy.

 

winter gas

 

Even if the tire is more exposed to the front air stream, has an affect.
Like everyone has already said. Tire pressure, size, tread pattern, weight, increase in rim width for larger tires. Anything thst you can imagine about tires can affect fuel economy. Hence all those MPG improving tires out there. They're not aggressive at all.
Add up all this. Winter gas. Longer engine warm up cycles. Wearing winter boots. Ice on and under a vehicle increases weight and reduces aerodynamics.
I'd gas up and immediately go on a long steady highway drive of a hundred 'plus' miles. Then gas up and work out your mpg by hand and see what it says.
At least you'll eliminate the numerous warm up cycles that your engine performs every tank of gas used.
I did that with my old truck when l lived in Canada. The results were much better. Still a bit lower, but much better.

 

So a bit more information may actually needed here (as some members have pointed out).

It's going to depend on a few things, you have a larger size than stock on the truck. So are you calculating your fuel economy with just the truck read out? Or are you adjusting your odometer to account for the larger diameter and then calculating at the pump?

Do you drive primarily city? Mixed? Or is this all highway?

How heavy of a right foot do you have?

These trucks (as many know) are not aerodynamically friendly and any highway speeds above 65mph will show large drops in fuel economy.

If you drive exactly the same route, style, etc and the only change is now the tire (brand/model/tread design/load rating), in theory you should have seen some sort of mileage increase due to the lower tire weight. This should help in rolling mass (less energy to get started/stop and less energy to maintain momentum) and also should help ride a bit to.

Only theory I have is the General tires actual have a higher coefficient of friction due to the tire compound and you might actually still be driving slightly more aggressive to account for the previous heavier tires. So say you mash the throttle to get up the on ramp with the heavy tires and are still doing the same thing with the new ones.
Passenger (standard load) tires generally have a sticker compound compared to the LT counterparts. Mainly due to them being on lighter vehicles so you need as much grip as possible. With heavier trucks the mass helps with traction and if you had a sticky compound it would accelerate the wear.
I also think with lower temps, now winter blend gas, and possibly an overambitious right foot, these might be offsetting the benefits with the tire change.

 

Best mpg setup I've found was
265/75/16 Hancook dynapro ATMs 37lbs each
FN Countersteer rims 19lbs each

I switched to a level 8 wheel and e load tire and saw an immediate drop in mpg as well as steering response.

If you are chasing best mpg make sure you have the lightest wheels too.

 

I got 6.8 ft/lbs. The change in speed needs to be in RPM. So a 30" tire will rotate ~673 RPM at 60mph.

 

Classic definition of a #spinner

Which one makes it harder? Number #2....oh for sure #2.

happy holidays ... sorry, i couldnt resist

 

I have the perfect video for a #spinner but it will totally get me banned

 

1.7%.... thats 1.7% less energy....thats not measurable i think on mpg


The difference between summer- and winter-blend gasoline involves the Reid Vapor Pressure (RVP) of the fuel. ... The US Environmental Protection Agency (EPA) says conventional summer-blend gasoline contains 1.7 percent more energy than winter-blend gas, which is one reason why gas mileage is slightly better in the summer.