Super Singles

[mchero]

Anybody running super singles on their class A???

For those of you unfamiliar with super singles they are a single WIDE tire/rim that replaces the duals on the rear axle(s) seen on some of the trucks on our highways.
They are very efficient BUT if you have a blowout your unable to limp to a station.

[Winnipeg]

Someone mentioned a very important point. They look cool! Are you really so concerned about a little bit of fuel economy when you drive a huge DP around? I confess that I have never seen a DP with singles, but I have seen dully pickup trucks where they have swapped the dual wheels for a set of very wide Mickey Thompsons. Very cool. So, live a little (more) and go for a cool look.

[moisheh]

The reason they won't improve your mpg is very basic. An over the road truck goes at least 150,000 miles a tear. A MH might go 8000 a year. You and your MH will be buried before there would be any pay back. I fi offered you some magic device that would give you 5% better mileage for $2500 would you buy it ? You see them on bulk haulers more than on dry van trucks. There is a weight saving and truckers that get paid by weight can haul more of their commodity

Moisheh

[timmac]

mchero wrote:
Zero spare here.

I never travel without one..

[mchero]

Zero spare here.

[timmac]

I will stick with duals, I can carry a spare, try carrying a spare Super Single..

[fortytwo]

Super singles have been around for about 50 years, at least. A fellow named Dick Cepek was selling them for folks using their trucks in the Baja in the mid 60's. I bought a set to install on the back of my Ford Camper Special pickup when the original 16 inch tires wore out. Gave more load capacity to carry the camper on the back. Never noticed any better fuel mileage. I thought they, being tubeless, were more reliable than the old tube type 750/16's. Never had a flat, but only a sample of one. As others have posted, best for flotation on soft ground, but of course I was replacing a single with a Super Single.

Biggest concern I would having using them is when you blow one on a long, lonely road in the West, where will you find a replacement?

[cross21114]

mchero wrote:
Thanks two jayhawks for the clarification.
Don't know how cement and trash trucks got in to this thread. Some confused people I gueas.

Europe adopted super singles much earlier than truck fleets did here. The first use of super singles (in my case) were on concrete block trucks which were allowed a GVW of 65,000#. The only way to do this was with a front axle rated to 20,000# and a tag axle. This required super singles on the steer axle. Concrete trucks have the same issues and assume trash trucks also but not in that business so don't know specifics.

[Groover]

TDInewguy wrote:
One more thing...

I really hated trying to check the air in the inner dual... I wonder how many blowouts happened from a tire being low to begin with?

The super single is easy to check air in.

I second you on that! I came very close to disaster before I got my TPMS and the valve stem extenders in the inners leaked most of their air out. My coach has small wheel openings and it is very difficult to see or thump the inners so actually checking the pressure is crucial. In my opinion you may be better off with duals if you do have a tire go out but you are more likely to have a failure in the first place. I have had a pickup technically totalled by flapping rubber from a separation and heard horror tales on what that does to a class A. Being able to move the coach a little ways after separation may be a minor issue.

Thanks for the info on the smaller size singles, I will probably be buying tires in about 2 years and will have to check into them. Since I have steel rims and heavy wheel covers I expect to save even more weight plus making it easier to check tire pressure. I just ran some quick math and those tires are 2 1/2" larger in diameter than the tires that the coach came with. Maybe they will have some closer in diameter by the time that I am ready to buy.

Food for thought: Statistically private planes with twin engines are more likely to crash than single engine planes. This is probably a combination of there being so much more to go wrong and a pilot not responding correctly to a single failure. Even in boats twins are not much more reliable than singles because what takes out one often takes out the other. If someone can find some hard statistics on single vs dual tires that would be very interesting. I like facts a lot better than opinions, even my own.

[mchero]

Thanks for the very informative posts on super singles. Just what I was expecting to see from the reading I have done on the trucking forums.

Hopefully some of the early posters have learned something new.

[TDInewguy]

One more thing...

I really hated trying to check the air in the inner dual... I wonder how many blowouts happened from a tire being low to begin with?

The super single is easy to check air in.

[TDInewguy]

Groover wrote:
The resistance to super singles reminds me of how hard it was to get truckers away from cross bar tread for the drive tires back in the '70s. Those things were noisy and really hurt fuel economy but some drivers would not give them up. All the same, it happened eventually. We have all carried spare tires for years but a lot of new cars(and coaches) don't come with spares anymore. A big chunk of the reason for that is simply that tires don't fail nearly as often as they used to and we just don't need to carry spares. That same factor might encourage us to switch to super singles if we can convince ourselves that we can live without the redundancy that duals give us.

My understanding is that super singles have reduced rolling resistance mostly simply because they are only flexing half the number of sidewalls that duals have. I have heard savings estimates of 5 to 10 percent. I would take that. Another advantage is the weight savings. From what I hear you can resuce the weight of an 18 wheeling by 650 pounds with super singles. Due to only having one fourth the number of duals we could call that 162 pounds for most class A's. That could also aid fuel economy and improve ride by reducing unsprung weight or let you carry that much more. One thing that I have wondered about is that it appears to me that a super single is narrower than two regualar tires with the spacing between them and would allow the shocks and springs to be placed farther apart, that could improve handling.

Even though super singles seem to be fairly popular in my area I don't recall ever seeing one one the side of the road with a flat tire. Maybe reliability is not the issue that we assume it is. Regardless, I don't think that they make super singles to replace the pair on 255/75/22.5's in the back of my coach so I don't guess that I will be trying them anytime soon.

My Winnebago had 255's on it, and I put the 445/50/22.5 singles on it with no issues. I just had the ECM reprogrammed to get the speedometer correct - and it was dead on accurate.

[TDInewguy]

A few other things I missed mentioning...

They are quite a bit lower weight - its about a 150 lb savings on the rear axle, and that is all unsprung weight.

If you look up on Michelin's truck tire website - the calcs for my RV show about a 7% fuel economy improvement going from the current XRV's to the Super Singles, and XZA2 Energy front tires.

As for a blowout?

Never had one.

But the tires are readily available across the country. All michelin dealers are required to stock them.

And for those of you talking about duals being better for a blowout, I disagree... if I drive overloaded on one tire - it will not be good for it, and may cause an issue where it will be the next to blow.

If you blow a front tire, you stop. If you blow a rear and keep driving - chances are you ruin the "good" tire. If you blow a single, you stop.

I drive 15,000-25,000 miles a year in my RV - so the fuel savings is worth it for me, and as I stated - the single tire is LESS money than two - after you pay for the rim.

The 1/2 mile per gallon improvement equals about $300-450 per year for me at current fuel prices.



And they are smoother.

🙂

[Groover]

The resistance to super singles reminds me of how hard it was to get truckers away from cross bar tread for the drive tires back in the '70s. Those things were noisy and really hurt fuel economy but some drivers would not give them up. All the same, it happened eventually. We have all carried spare tires for years but a lot of new cars(and coaches) don't come with spares anymore. A big chunk of the reason for that is simply that tires don't fail nearly as often as they used to and we just don't need to carry spares. That same factor might encourage us to switch to super singles if we can convince ourselves that we can live without the redundancy that duals give us.

My understanding is that super singles have reduced rolling resistance mostly simply because they are only flexing half the number of sidewalls that duals have. I have heard savings estimates of 5 to 10 percent. I would take that. Another advantage is the weight savings. From what I hear you can resuce the weight of an 18 wheeling by 650 pounds with super singles. Due to only having one fourth the number of duals we could call that 162 pounds for most class A's. That could also aid fuel economy and improve ride by reducing unsprung weight or let you carry that much more. One thing that I have wondered about is that it appears to me that a super single is narrower than two regualar tires with the spacing between them and would allow the shocks and springs to be placed farther apart, that could improve handling.

Even though super singles seem to be fairly popular in my area I don't recall ever seeing one one the side of the road with a flat tire. Maybe reliability is not the issue that we assume it is. Regardless, I don't think that they make super singles to replace the pair on 255/75/22.5's in the back of my coach so I don't guess that I will be trying them anytime soon.

[TDInewguy]

Hey everybody, I'm the person that has personally driven about 100,000 miles in my class a motorhome and super singles.

Why did I buy them? Well when I bought them I was on the quest for maximum fuel economy because at that time Fuell was over four dollars a gallon.

What were the benefits?

Lower rolling resistance, Wider track than duals. (Yes the mathematical width is wider than duals, even though the outer dual sticks out further), better rear brake drum cooling as its not completely engulfed in the inner rim, great traction, smoother ride...

Drawbacks?

You need to buy new rims.

The sale of my aluminum dual rim paid most of the single rim cost, and the super single was slightly less expensive than two rear tires.

Would I do it again?

Absolutely! I just purchased a 2009 Newmar Allstar that has 10 year old XRV's on it and they frankly are much worse on the snow than the super single was on my Winnebago that I just sold (with a new set of tires...)

So count all the pennies you want, I like them and will use them on my new coach.

At $2 a gallon it won't save me as much as it did back at $4, but I like them.

As for fuel economy - over the 9 years I had my Winnebago - I started out in the 7-7.5mog range and sold it on a 3 year running average of 8.89mpg.

Part of that was the tires, part was all the synthetic fluids, part was driving habits.

I would say that at least 0.5mpg was directly due to the tires, if not more.

On my Newmar - I will run my first trip with the old XRV's and then buy all new tires - so ill have another sample to share.

If you read up on MPG and your coach -- below 50mph the rolling resistance is the single largest contribution to fuel use, and above 50mph its wind resistance.

[mchero]

Thanks two jayhawks for the clarification.
Don't know how cement and trash trucks got in to this thread. Some confused people I gueas.