Quote:
Originally Posted by Ecky
Great article. I find it interesting that they tested them at 26 PSI. Looks like bias ply isn't necessarily much worse than radial, but the tires tested from Continental and Semperit were well below the rolling resistance of the other brands.
|
A couple of thoughts:
That paper was from 1978, and the tires were from vehicles produced as early as 1974! that's why the bias tire pressures were as low as 26 psi. That was the pressure that was sometimes used in those days.
Plus, all those tires were OE. Nowadays the RR values for OE tires is considerably lower than for replacement market tires - but back then??
If I had to fault the writers of the report, it would be that they didn't mention that it was very likely the radial tires had harder, more wear resistant tread compounds than the bias tires. That would also mean that the radial tires could have achieved better RR if they used the bias tire tread compounds.
And then there is the business of tire size. We now have evidence that tire size plays a role in RR - and larger tires are better than smaller tires. Their data seems to point that direction.
And brand? If I remember correctly, they said that this might be due to the particular tire size they tested. Besides we are some 40 years after that paper and a lot of research has taken place. I wouldn't draw any conclusions from the brand data because the data is so old. My experience is that there is very little difference between brands - that the difference between an OE tire and a replacement market tire is way, way more different.