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Old 12-29-2010, 11:47 AM   #56 (permalink)
CapriRacer
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Quote:
Originally Posted by Ryland View Post
As I understand it the reason for a wider tire offering less rolling resistance would be that the weight is spread out over a wider area the contact area is shorter, or more so the flat spot made in the tire by it pressing on the road is smaller.
Now most cars that call for 155mm wide tires are pretty light in weight (less then 2,000 pounds) so you have about 400-600 pounds resting on each tire, the point then would be to figure out how wide you could go before you no longer see a return on reduced rolling resistance, right? and for say a 1,800 pound geo metro that for years were sold with 145mm wide tires it seems like 155mm wide tires are going to be about the right size if you can find them in LRR and that seems to be the original topic.
Am I mistaken that the idea is to keep the flat foot print of the tire as short as possible?
I think the right way to look at this is that RR is stongly related to deflection.

In the same way that more inflation pressure improves RR, less load also improves RR. It's not a stretch to say that decresing the percentage of rated load also decreases deflection - ergo RR - so using a tire with a larger load carrying capacity, but at the same load and inflation pressure, would also decrease the RR.

And the fact that the footprint gets smaller is an artifact of reducing the deflection.
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