# Low Rolling Resistance Tires Worth It?



## PeterH (Mar 20, 2009)

Hi there,

I expect to pick up four factory steel rims that I sent out for powder coating, today. I got them from a local salvage yard so they were solid but fairly ugly. 

I'll need new rubber today so my question now is what type of tires to use. 

Are low rolling resistance tires worth the cost and effort?

I also need to decided if I'm going to use snow tires or summer tires... we are expecting a lot of snow this winter and I want this rig to see the road before the winter is over... normally I'd use studded snow tires like I do on my ICE vehicles.

Thoughts anyone?

Thanks,
Pete


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## dtbaker (Jan 5, 2008)

I had a hard time FINDING LRR tires in 13", so just went with Kuhmo solus kr21 for summer tires. I am not fan of studs as they rip the crap out of the roads and seem worse on dry, I prefer a good snow like Blizzaks (not avail in my size), or Firestone 'winterforce'.


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## spdas (Nov 28, 2009)

I would also be interested in a comparison between a before and after installing LRR tires. KWH per mile difference with all the other variables constant.

francis


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## DavidDymaxion (Dec 1, 2008)

The gas mileage goes up with Blizzaks on my gasser. They have awesome winter traction, but give the car a rubbery feel for handling and steering feel.


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## spdas (Nov 28, 2009)

DavidDymaxion said:


> The gas mileage goes up with Blizzaks on my gasser. They have awesome winter traction, but give the car a rubbery feel for handling and steering feel.


How much "UP"?
thanks
francis


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## DavidDymaxion (Dec 1, 2008)

About 10% better. Since the car does most of its miles at freeway speeds I'd guess that's around 20% less rolling resistance than high performance summer tires. YMMV 


spdas said:


> How much "UP"?
> thanks
> francis


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## spdas (Nov 28, 2009)

Well as soon as i get tired of burn-outs on my old Nitto195-50-15's I will buy some LRR 185-65's. In the meantime I have some Bridgestone Potenza 185-60's mounted on stock narrow rims that are a full one inch narrower to see if I get any difference. Both are used tires and worn-in, but do not know which was better LRR to start with.

**EDIT** I cannot find any info on LRR to my above tires, but the Nitto has a 300 treadware, which is 3x better than a "test tire", so I assume it is a harder rubber and thus maybe a better LRR? The Potenza is a 160 treadware and is a 1.6x better than a test tire and assuming softer rubber and maybe not as good a LRR? But there should be enough info to judge if there are significant differences to warrant being anal about choosing a LRR tire. (my Nitto 50's make my Yaris handle like a go-cart)


Francis


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## EVfun (Mar 14, 2010)

I don't know about high tread wear lowering rolling resistance. The first gen Prius had one of the LLR rated Potenza RE92 tires and it was lucky to get 30k miles from a set. I think almost all new passenger cars get a tire that is at least partly an LLR tires because it helps them meet the corporate average fuel economy (CAFE) standards.

If a skinny LLR tire is a concern, there are the tire sizes for the Smart car. I have a set of 2006 fortwo coupe OE type front tires on my beach buggy. The size is P145/65R15. There are also P175/55R15 tires used in the rear and P155/60R15 tires used on the front in later years. All of these are only about 22.5 inches tall.


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## spdas (Nov 28, 2009)

"The first gen Prius had one of the LLR rated Potenza RE92 tires and it was lucky to get 30k miles from a set."

Well that at least confirms tire wear of only 160 for this tire. Was this tire touted as a LRR on your first Prius? Or bak then was LRR not such a big deal even in a "mileage" car?

francis


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## EVfun (Mar 14, 2010)

Very much touted as an LLR tire and it was an LLR tire because when I replaced the tires the fuel economy dropped around 1 mpg. Other Prius owners reported similar, or even larger, reductions in fuel mileage. 

I have no idea if LLR tires help on the front of my EV Buggy, but they where slightly shorter than the P135R15 tires it had before. The old tires where a glass belted radial, not steel, intended for a Citroen 2CV.


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## spdas (Nov 28, 2009)

Ok then I shud notice a good improvement to report going from my Nitto's @ 6.5" wide and to the Potenza's (LRR) and 5.5" wide. I will have to factor in that the Nittos will show 5% more traveled miles as they are a lower profile
francis


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## spdas (Nov 28, 2009)

Here are a couple of sites to read up on LRR. Claim is made that larger and somewhat fatter tires are better LRR.

http://ecomodder.com/forum/showthread.php/top-5-most-fuel-efficient-tires-lowest-rolling-2813.html

http://www.barrystiretech.com/rrandfe2.html

Confused at this stage.

Francis


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## PeterH (Mar 20, 2009)

I'm a bit confused also... the local dealer didn't really know much about LRR tires. It is their busy season as they rush to put snow tires on everything. 

I just went with Toyo Observe G-02 Microbit Studless snow tires because I'm hoping to put this rig on the road while there is still snow on the ground. I'll just have to live with the fact that I'll have much better range in the summer. 

Pete


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## madderscience (Jun 28, 2008)

I'm quite happy with the bridgestone B381's I bought for my MR2. Only real issue is that they are a size too big for the car, which is hardly a fault of the tires, but they only came in that one size at the time.

Last time I tried to measure it, My best estimate of dry weather, concrete surface rolling resistance ratio for my car was 0.01 (or 1% of the weight of the car) If you believe the B381 ratings, 0.6% of that is the tires, and the rest would be brake drag, bearings, and other driveline friction. Traction and performance tires can be double or triple the rolling resistance of a LRR tire.

To put the 0.01 ratio in context, for my car that it the about the same amount of drag as the aerodynamic drag at 50mph (35lbs or so). So if that 0.01 number were more like an "average" car (0.02 to 0.03) you can see that it would definitely hurt the range.

So IMO, LRR tires do make a big difference. If you can't find a real "eco" or LRR tire in your car's size, then the next best thing to do is go for the highest PSI one you can get. Passenger car tires are available in up to 51psi I believe. 

Good luck.


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## dtbaker (Jan 5, 2008)

madderscience said:


> I'm quite happy with the bridgestone B381's I bought for my MR2. ...
> To put the 0.01 ratio in context, for my car that it the about the same amount of drag as the aerodynamic drag at 50mph (35lbs or so). So if that 0.01 number were more like an "average" car (0.02 to 0.03) you can see that it would definitely hurt the range.



the problem for me has been I have not found a handy chart of what the options are, or posted values for 'regular' tires.... especially in a 13" wheel size.

when I was running lead-acid, I didn't want to even consider low-profile because it would have given a much harsher ride harsh ride with all the added weight, and we have pretty crappy roads and lots of 'speed humps' on residential streets. With Lithium and stock weight I might consider moving to 14" or even 15" and low profile to get a more 'normal' size.


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