Bearing losses wrt rolling resistance.

[dootdootdoot]

I've seen that increasing tire/wheel diameter can reduce rolling resistance marginally and was wondering if this was hogwash or not. I was thinking it could be a possibility if bearing friction is higher than the rolling friction between the tire/road, so increasing the speed of the outside diameter compared to the speed of the bearings could reduce those losses, which (along with different tread, higher pressures, and different rubber compounds) may also be why bicycles generally have much lower rolling resistance... But that's just speculation.
TIA

 

[GregLocock]

Bearing drag is fairly low compared with tire resistance, but increasing the ratio of wheel diameter to bearing diameter will help. A little. Big tires can have less rolling resistance than small tires, but will have more aero drag.

Cheers

Greg Locock

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[dootdootdoot]

Huh, given how much aero drag increases I wonder if it's a trade-off? Thanks btw.

 

[GregLocock]

Depends on the operating regime of your vehicle, and a whole lot else.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[patprimmer]

If the extra size is contained within existing bodywork, there should be little difference in aero.

If the width, load and pressure are the same, bigger diameter should have less tread and sidewall distortion, so it should have lower losses due to hysteresis, however it will have a higher polar moment.

Regards

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