Jim:

I have heard of a spec for tires called "rolling friction", which supposedly indicates how much resistance the tires put up to being driven in a straight line. It would seem that this spec. when considered by itself, would indicate that a tire with low rolling friction would require that less torque/hp. would be used in driving the car (or in the alternative the car would be faster), and better gas mileage would be obtained. But I notice Tirerack's specs on the internet do not include this spec.

Could you briefly explain the concept of "rolling friction" (AKA rolling resistance), and let us know where we might find that spec for tires you sell?

Thanks,
Richard

 

You won't find those specs anywhere. A lot of the newer tires do use lower rolling resistance tires but I have not seen any numbers. The S03 is a lower rolling resistance tire than the S02.
Sorry I couldn't be of much help.

Jim

 

Jim:

Thanks anyway. The only place I've seen "rolling friction" or rolling resistance" mentioned and quantified as a tire spec was in a magazine that does not like to be quoted whose initials are C.R. Is there any one else out there that has ever heard of this? I'm only interested because a tire with low "rolling friction" might be a way to SLIGHTLY help the S2k's notorious lack of low end torque.

Thanks,
Richard

 

4.44 gears will get you 8% more torque and 4.77 gears will get you 16% more torque. Why not go that direction?

I don't think a difference in rolling friction is going to be that great.

 

Well, rolling friction happens when a round shape like a tire deforms at its ground contact point and forms a slight "flat" area contacting the ground.

Ideally, rolling friction wouldn't exist, and the tire would only contact the ground infinitesimally (1 dimensionally).

So, I would imagine less rolling friction should mean more net torque at the wheels.

It could be more complicated than this though, I'm only a physics _minor_

 

The only reference I've seen to 'rolling friction' was in terms of 'rolling resistance' on gas/electric hybrids. They use the skinny super hard tires at high psi to minimize tire deformity. This helps them squeeze out a little extra mileage, but they suffer in performance as a result.

Based on that, I would presume that low rolling friction and high grip are mutually exclusive. I'll go for high grip, thank you very much

 

The sole place I ever saw stats on rolling friction was in a magazine called "Consumer Reports" (which will probably sue me for using their name). They had a big tire rating article a couple of years back, and included this spec on all rated tires. As I had a Miata at the time, I was naturally looking for the "least resistance" I could find to make up for super wimpy power (actually, my wife's car). Bought on that basis, and it actually did some good in acceleration. Am suprised that no one else has heard of this spec. Wouldn't choose a tire for an S2k on this alone, as I can easily see how low rolling friction might adversely impact high speed handling. But would consider it as one of many factors, if it were available.

Thanks,
Richard

 

This is generally measured with a "coast down test" and this means that different tires are mounted on a vehicle (or changes made to the tire pressure) and the vehicle is rolled down a slight incline and left to roll to a stop. the distance covered is measured. The next test is made and measured, etc. The data is compiled and compared. The longest rolling distance is the tire with the least rolling resistance. The more tire pressure you have, the lower the rolling resistance your tires will have.

For our cars, the lowest rolling resistance is not necessarily desirable. I would think that the OEM S02's probably would have very high rolling resistance, wide footprint and sticky rubber with much tread on the ground. A tire with low rolling resistance would have a very narrow tread with hardly no rubber touching the road and would be running high pressure. It would have practically no flexing in the tread or sidewalls and would have a very hard rubber compound. This might work on the Insight, but not the S2000.

 

IMO, the OEM tires would have less rolling resistance compared to other tires of same dimensions (if there's any?). The sidewalls are pretty stiff and so is the tire overall. Yes the rubber is stickier than other tires but it does not come into play that much when you're driving straight at highway speeds. Other softer tires will have more rubber to the ground at highway speeds, like "Zich" said:

"....l, rolling friction happens when a round shape like a tire deforms at its ground contact point and forms a slight "flat" area contacting the ground...."

This is why I say there'd be more rubber to the ground if the tire's construction is overall softer. What makes the OEM tires grippier is the nature of the rubber, not the construction of the tire (which is responsible for the handling).

I have used the Toyo Proxes T1-S tires on my S2k and when I switched back to the OEMs for a while the first difference I noticed was the OEMs had a LOT less rolling resistance compared to the proxes. I could not believe the difference, it was much easier to drive the car on the OEMs.

I always complained about too much engine braking and it was making my car very twitchy in the curves (normal driving at low RPMs), the moment I'd take my foot off the gas, it felt like I had hit the brakes. I knew this was a characteristic of the car but switching back to the OEMs I realized that it was not as "bad" as with the proxes. The proxes offered a lot more resistance compared to the OEMs. Keep in mind that the proxes were almost an inch narrower than the OEMs - even in 245/45/16 size.

I have not used the S03s, but if they have the same construction (stiff sidewalls,etc) as the S02s then they would have less rolling resistance since they put less rubber to the ground (S03s have wider water channels).