looking @ new tires

I didn't realize the Yokohamas were that low RR. Great price too -- what is the tread depth?

If you act fast, there is someone on the facebook 9+ mpg club offering a straight trade to go back to duals...

The michelin line energy D's are what I run. 89 rolling resistance, 24/32 tread depth, but they are $1100 new (I bought mine used). You may have run on them while at Con-way. Not great in snow & they are more prone to stone drilling than most, but they roll great:

 

you may have a long time to decide. Some tires wear like iron the less tread they have and that is also the best RR, fuel mileage tire you will ever have on your truck. One with less than 5/32 tread. I wouldn't be surprised if you could go til fall 2016 on those.

 

Michelin has 4 drive tires ranked 1-4 1 having the lowest rolling resistance
Michelin X line energy D is number 1.... thats what i have
Michelin XDN2 is number 3
when i changed from the XDN2's to the energy D my MPG went up .5 MPG
the company i'm leased to gives me a discount... (National account) 8 drivers was $3,200, thats $400 each out the door

 

DY, do you have numbers as far as fuel mileage goes comparing super singles to duals? Or anyone else for that matter?

 

So is that how they get these claimed low rolling resistance numbers, by making a tire with less tread depth? And charging the same or more than a higher rr/depth tire?

 

Careful, the Xone line energy d (wide single) is 89. The x line energy d (dual) is 109.

Con-way had Tag axles though, so they were the worst-case scenario. At con-way I remember occasionally having to lock the drive and dump air to the tag to slide tandems. On dry concrete...

I haven't had that problem with singles + twin screw. But I've spun the tires a couple times on a wet onramp...

My advice: save money now. Don't "throw your tires into the ditch" until you have a good feel for your truck's reliability and have built up a good cushion. Fuel is still pretty cheap right now, the payoff just isn't that big (and may not be there at all if you have to buy wheels too).

Unfortunately, when I converted I wound up moving my 75% lugged drive tires to my trailer, replacing 2/32 trailer rubber (about as low RR as it gets). So I did not see an improvement and may have even seen a slight decline. Once I replaced the trailer (new one came with low rr tires), my mpg immediately shot up 10%.

Unfortunately part of that was from the side skirts, so I just have no good data.

I do believe Michelin's RR calculator to be reasonably accurate though.

Low tread is definitely part of it. Casings, compounds, & tread design are also very important.

If a 32/32" tire has a RR of 100, that exact same tire at 6/32" would have a RR of ~80. That same tire at 24/32" would have a RR of ~93.

With DOT-legal race tires, people often have their tires "shaved" to become full slicks. Better grip (in the dry) and less rolling resistance... I imagine we'll see tire shaving more and more with hyper-miling semis in the next 10 years.

Take that hypothetical 32/32 100 RR tire. Shave it to 24/32 and increase fuel mileage by ~7% while decreasing tire life by ~27%. If fuel costs 50cpm and tires cost 5cpm on 32/32" tires -- 55cpm total, your cost on 24/32 tires would be 46.5cpm fuel & 6.4cpm tires -- 52.9cpm total (plus whatever tire shaving cost -- currently ~$15/ tire for car tires).

 

we have one trailer with super singles no tractors
the driver with that trailer makes same run i do and gets .2-.3 mpg
better then me but is also willing to drive slower to get it
he also replaces trailer tires sooner then me so I don't see the gain
owner hasn't bought any more SS and we all have new tractors