Very much prefer my winter wheels and tires

[skyking]

Wheel' find out about larger tire size on my truck
I am putting on my 34" traction tires that were on there when I got it. higher OD ratio offset by added mass = hmmm?

 

[JCH13]

Although you might get lighter, larger rims, the rotational inertia equation has the radius squared, and larger wheels have more of the mass farther from the rotation's center, so the cards are really stacked against you.

This is true. However, there is a lot of design detailing that comes into play here, and wheel designers are getting quite creative:

Mmmm... carbon fiber drum....

Hollow 18in VW GTI OE wheel:

Wheel' find out about larger tire size on my truck
I am putting on my 34" traction tires that were on there when I got it. higher OD ratio offset by added mass = hmmm?

You'll be extra-sad for the increased torque load on your brakes and changes in gearing.

Edit: I wonder what, if any, towing de-rating should result from having a larger wheel diameter...

 

[skyking]

Diesels behave differently. When I went from the stock 3.73 gearing to the 3.42 and cut the RPM by 9%, I picked up an instant 15% in MPG. It was shocking.
The best I had in over a year was 19, and the first short tank I tested was 22 @ 62 MPH.
Peak torque on my engine is 1600.
60 MPH = 1620 RPM with the stock tires. the 34" will drop it 10%. It really will be interesting to see.
Yesterday I was towing 8500 pounds on I-5, and the % load was around 40% at the low end and 75% at the high end at 1650 RPM. The bare truck will be little to nothing, so the only holdup for collecting good data is the weather. Winter just sucks for that with snow and crap, cold temps. All of them hurt MPGs.

 

[JCH13]

I'm not sure what you're getting at... Taller gearing (from gears) is almost always beneficial in fuel economy, but taller tires effect that change differently than actual gears because of their effects on things like aerodynamics and rotating mass. These changes occur on both diesel and gasoline powered trucks...

One could speculate that because diesel trucks are generally built with stronger components than gasoline trucks that the towing efficacy might not change much, or at all, from a component durability perspective. That's possible. But the reduction in braking capacity is a real bummer. The extra height increases weight transfer, which is also a real bummer.

Here is an interesting experiment into the effects of lift kits and taller tires on the braking and roll-over performance of a truck (1992 F150). There is decreased braking performance and decreased vehicle stability as the body is lifted and as the tires get larger. I doubt you're going to start rolling your truck all over the place, but you'll likely notice that you need to press around 10% harder on the brake pedal to get the same stopping performance.

 

[jlee]

I'm not sure what you're getting at... Taller gearing (from gears) is almost always beneficial in fuel economy, but taller tires effect that change differently than actual gears because of their effects on things like aerodynamics and rotating mass. These changes occur on both diesel and gasoline powered trucks...

One could speculate that because diesel trucks are generally built with stronger components than gasoline trucks that the towing efficacy might not change much, or at all, from a component durability perspective. That's possible. But the reduction in braking capacity is a real bummer. The extra height increases weight transfer, which is also a real bummer.

Here is an interesting experiment into the effects of lift kits and taller tires on the braking and roll-over performance of a truck (1992 F150). There is decreased braking performance and decreased vehicle stability as the body is lifted and as the tires get larger. I doubt you're going to start rolling your truck all over the place, but you'll likely notice that you need to press around 10% harder on the brake pedal to get the same stopping performance.

"The combination of a 3-inch body lift kit and 4-inch suspension lift kit"

jfc..

 

[skyking]

Yeah, I get the math. I'm increasing radius by 1.5"

 

[JCH13]

"The combination of a 3-inch body lift kit and 4-inch suspension lift kit"

jfc..

Right? Still, people do that...

Yeah, I get the math. I'm increasing radius by 1.5"

In that report I looked at the tire OD changes that were around 10%, and that change still showed a measurable difference. I am quite interested to hear what you report back with!

 

[skyking]

will do
I took a 1.25" block out of the rear of my truck, as opposed to most guys who get a "leveling kit" that adds 2" to the front. I don't care for lifted trucks nothing personal lifted guys, it's just not for me. I hope to bag the front and rear and lower the whole truck at highway speeds about 2.5", but that is going to take some cabbage.

 

[skyking]

I did not have a good time today.
Traction tires advised, no big deal right?
Sat for two hours, probably a half hour total of idling. Jacknifed semi. Two cars lose it right in front of me in the slush and eat the guardrail. Half hour of 10 mph getting by the semi wreck.
Another half hour in 4wd at 30~40 mph on various shades of ice.
I still managed to get better than 21 mpg.
I weighed the factory steel wheels and BFG stock tires, 87 pounds.
The aftermarket steel wheels and 33.7" nittos weigh 99 pounds. Wheel size is the same, just a higher profile larger tire.