If you are using the truck to tow that 15k you will get better mpgs with the 4.10. I say 1-2 mpgs better. If you are interested in maximizing mpgs while empty hwy driving than the 3.55 should be better. Tire size also can play a big part in this also. There really is very little reason to get a 3.55 if one plans to use their diesel to tow with.
Personally I would want a 3.73 in a SRW 6.7.

 

Give it two years, and perhaps the transmission will change, like it did in 2009 for the F-150 before an engine change in 2011.

On the other hand, GM has been running a 6-speed Allison auto for a decade now in their HD trucks. I'm actually OK with a 6-speed, but like I said - it would be nice to have the short axle ratio for heavy towing in lower gears but then extra tall gears in the trans for fuel efficiency on the highway.

My only complaint about more gears is that the trucks become slower.

 

^^This would have been my preference as well, but alas...

 

This is the tire I want to put on my 6.7, 3.55, 20 inch SD. This tire is 32 inches and the next would be closer to the Michelin original size of 34 inches. If I need more gear I will get the tire in the pic. If I am happy with the performance I will get the 34 inch profile of this tire.

[ATTACH]154168[/ATTACH

 

Couple of problems you run into by doing that. One is that the load rating is a little less on the tire you want. Another problem would be reprogramming the speedometer. Ford can do it, but that size is not in the system. Another possible issue is that ride quality would suffer. Why would you want a shorter tire that reduces ground clearance and degrades the look of the truck?

 

I hope you take the bow tie off before putting them on a

 

Seriously though as to the Cooper tires themselves: how is the road noise? how many miles do you get useful tread life?

 

I've got the AT/3 on my Super Duty and I really like them. Better traction than and similar noise to the GY AT/S that were on it before. I've got about 10k on them and they seem to be wearing well, but time will tell.

 

Thanks. I am considering purchasing separate steel wheels for winter and outfitting with a more true winter tire than the stock Michelin's. I have been using the Michelin's (AS) for 16 years in the LR E and I am fully satisfied for my normal use. I really like wearing them down over the summer when the timing is right and then replacing in November for the winter. Last set ran 65K miles and could have gone farther legally but it was time to change. Toyo has an equal or higher load rated and mileage rated tire and I also consider them for a winter tire. I am tired of having nice rims with the ill effects of winter emblazoned forever on the surface and corrosion on the bead which inevitably results in slow leaks. https://www.toyotires.com/tire/patte...k-winter-tires

 

You can likely find a set of take-offs with AT tires for less than new steel wheels and tires. I did the same with my F150, and get a set of new 18" take-offs from an FX4 for less than just replacement tires for my 17" XLT wheels. Then you can keep the stock look in the winter, and have nice fresh wheels the rest of the year.

 

I have many friends and personal experience with Cooper. Surprised at the response, thought these were more common. Have not heard of any problems with this brand. Load range E and they run quiet. Anyhow... buy what you want, just MHO.

 

Good idea. I have seen some nice values on take offs, some with good rubber too!

 

Cooper is popular around my area too. A couple of comments about tread wear but that was on automobile sizes. Take those comments with a grain of salt as well due to alignment/maintenance/driver is never an issue. "It's the tires, man."

 

Yeah, I'm hoping the mid model refresh will show up with a 7- or 8-speed transmission, at least for the gas engine. It might be too expensive to develop one that's capable of handling the PS' torque.

Of course, then we're talking 2019 or later and then everyone's bringing Level 4 autonomous driving out in MY2020/21 (for the sedan world).

It would be pretty sweet to have the SD take over highway driving through TX, NM, AZ, and NV, though.

Don't mean to take the thread too far off topic with future musings, though.

 

Lets go a little farther off. I am not ready to take my hands off the wheel for any electronic gizmo. Period. And there are places on earth even the inventors would be crazy, even in NV as mentioned. I think of one place in particular, although interstate, you better have your smart cap on when hauling a load through. The Virgin River Canyon is breathtakingly beautiful. And breathtakingly startling when you round a bend with a 6000 pound $100K boat in tow and the traffic is stopped dead because someone did not realize that 90mph on switchback curves on a 6% downgrade is not really the right way to navigate toward seeing the light of day tomorrow. Here is a video of the stretch. The better portion in my mind is heading south (second half) but I have twice come up on traffic completely stopped. And I have only made the trip twice, once each way. And just to keep the post on track, the 3.55 gears work great in these interstate hills.