MPG difference 9.00x20 vs 11.00x20

[merlot566jka]

It was said I wouldn't be able to measure the difference in fuel mileage if I swapped to single 11.00x20 radials from my stock 9.00x20 NDTs.

I don't think that's right. I mean, traveling at 55mph with either set of tires, its going to require less RPM to spin the taller tire, so how does it not save fuel!?

I'm about to make a 2200 mile trip, and every bit of fuel savings helps. I have a set of single 11.00x20s sitting in the yard and a set of 9.00x20s on the truck now. I wanted to swap them to save fuel and because they look better. But if there is no savings in fuel, screw that! I'll sell the singles!

So is there a measurable difference between the two?

 

[91W350]

I have been driving one on 1100 singles, radials, they would be worth the swap on a long drive for the difference in ride and drive. There is no rut seeking, they seem to absorb a lot of the bone jarring. I never checked mileage but I can vouch for the ride.

 

[dittle]

You may or may not notice a lot of difference. Taller tires equals less RPM but more mass to turn. So what improvement you get by taller tires has the possibility of being offset by the additional power requirements to turn those tires.

 

[Recovry4x4]

If you are seriously concerned with mileage on your impending trip, follow these tips. Regulate your maximum speed to 52. Fuel mileage above that speed goes down exponentially. Invest or fabricate a set of desplined hubs/blank caps for the front drive flanges. Remove the axle shaft from the fwd rear axle on the drivers side, cover up with one of the front drove flanges. Doing this will severely limit off highway travel but free's up a bunch of drag on the highway. Decrease wind resistance where possible. If you don't require a cargo cover, don't use it. Maintain maximum pressure on tires, especially fronts.
These are the easiest most cost effective way to increase your highway mileage.

 

[AndyC]

I take out my rear most driveshaft for long trips.

 

[rrrr]

I didn't notice a fuel savings when I switched to 395's. However, I run around 57 mph instead of 47mph. If I where to slow down to 47 with the 395's then I don't know if there would be a difference or not ? The singles ride better for sure.

 

[bugwugger]

Regardless of the mpg's top speed ie better. I average 60 puchable to 65 on the 1100. If anyone is worried about better mpg, sell your truck and buy a scooter.

 

[militarysteel]

i think my truck get's much better HP, and MPG when i have atleast 20% Engine oil added to fuel,
i am still wondering if removing FAN, replacing with electric has gains,

I'd also say go through all your wheel bearings make sure they are packed and snug, add lucas to the all the axles, Add lucas to the transmission, Transfercase, engine,

 

[dittle]

Single it out might help some. Less tires to turn, but it also depends on what you put back on for tires (added weight).

 

[Ferroequinologist]

I got at least 1mpg better when I went to 11r20s on the m109

 

[merlot566jka]

hmm, good responses. I am not looking to modify a bunch to save fuel, the trip is taking place in less than 2 weeks and I have a considerable amount of work to do at home before hand. So that leaves me in a crunch for time to order anything like desplined hubs, selectro's or anything of that nature. Plus I may end up in a situation where I need all 6 tires spinning...

Fuel mileage is a concern, but not a deal breaker. I have budgeted for an average of 7mpg. Anything more and I am saving money, who doesnt like to save money? Anything I can do for free, is FREE! Tire pressure for sure will be as high as I can safely run it. I have already added a K&N filter, changed diff and trans fluids, changed filters, etc etc.

Since I already have the 11.00x20 tires, it seemed logical.

Some folks say increased rotating mass, but I can swear removing four tires would decrease the mass considerably. I cant imagine that 1 single 11.00x20 tire ways more than (2) 9.00x20s. Plus rotating mass should only effect braking, coasting, and handling in this type of situation. Surely, if I were adding something that was 10x as heavy as the stock tires we would see a difference in acceleration and force required, but I am taking away mass as refernce to weight.
Yes it does take more torque to accelerate a lower ratio, but once its moving, the force required to maintain shouldnt be of any signifigance to warrant worse mileage. (same way it takes more power to light a lightbulb than it does to keep it lit) Basically this is an overdrive. Or an increase to the overdrive.

Not going for speed here, but would like to maintain around 55mph on the major highways. I dont want to become a hazard on the highway for driving too slow.

The stock deuce ride doesnt bother me at all, but if it makes it better, thats great!

 

[dittle]

On the mass part I missed where you said you were going to single it out. Yes, that would help.

 

[merlot566jka]

I got at least 1mpg better when I went to 11r20s on the m109

7mpg, 2270 miles, $4.00 per gal, = $1,297.14

8mpg, 2270 miles, $4.00 per gal, =
$1,135.00

difference = $162.14

Thats not a whole lot, but if I saw that missing from my checking acount, I would be mighty angry.

What would that buy... toys for my daughter, parts for the deuce, nice steak dinner for some SS forum members, a lot of beer....

 

[Recovry4x4]

If you want free and easy, just remove one axle shaft from the rear. I prefer the fwd axle on the drivers side. You can fab a cover out of a piece of plywood. Eliminates drag from mismatched rear tires, impoves turning radius and is probably the single most driving improvement you can do. Trust me it's worth it and only a few minutes.

 

[militarysteel]

some Filipino lady friends, Ohhh YEah!1

 

[merlot566jka]

Ha, I bet it would buy some of that too.

 

[73m819]

Just a note, I drove HndrsonJs deucs from ga to wi, doing about 55mph most of the way, it had 900s, about 8000# in the back, it got very close to 10 mpg, this was an EXCEPTIONAL running deuce, so can not say all deuces will do this.

 

[merlot566jka]

That's a good sign! Mine runs well, but has been turned up a bit so it smokes a little. EGT at full load is 1100 and 11psi boost.

 

[merlot566jka]

11.00x20 single wheels and tires have been listed for sale in the classifieds. Some one buy them!

 

[Varyag]

I singled mine out with g286 11x20s and there is a slight increase in mileage. I get around high 10s with mine. 52 on the GPS is 2200 RPM. The lower engine speed alone would be worth its weight in gold on such a long trip.

When doing long trips I keep it right at 52, 45 on the speedo.