Thoughts on tyre drag.

Sorry I missed in the last bit of my last post that for the extra tread drag to be offset the tyre needs to go up in Diameter.

Happy Days

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Originally Posted by joel0407

Did your fuel consumption get any better or just more consistent?

What size were/are your 33" tyres and are they wider than the 29" tyre? I'm guessing that if they were not that much wider the extra wind drag was offset by the better (less) rolling resistance of the larger diameter tyre.

Happy Days

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The fuel consumption was more consistent overall, but economy is better with corrected gearing around town.

The 29's were 235/70-16, the ST's and STT's were 255/85-16, the JT2's were 33x10.5-16.

Personally, I really don't think that wind drag has that significant affect on the consumption. However, I think the varying rolling resistance of tread patterns does. That's something that is notable between changing between like sized tyres but with different tread patterns, but I don't recall off the top of my head being notable when I changed from 255/85-16 Cooper STT to 285/75-16 Goodyear MTR which are comparably open pattern but one wide and one narrow.

Quote:

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Originally Posted by joel0407

Sorry I missed in the last bit of my last post that for the extra tread drag to be offset the tyre needs to go up in Diameter.

Happy Days

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Going up in diameter may decrease rolling resistance by a few percent.

Changing tread pattern can double rolling resistance. One is never going to compensate for the other.