Tyre rolling resistance

[iloveboost]

There was a discussion on here the other day about rolling resistance.
Some guys said that soft sidewalls lower rolling resistance but doesn't a solid wheel have no rolling resistance? I mean there's a little friction from the weight but that's it.
So surely a soft sidewall increases rolling resistance, and a low rolling resistance tyre also has harder tread?

Edited by iloveboost on Monday 21st July 10:59

[anonymous-user]

Yes, that's one of the reasons why an inflated tyre had less rolling resistance than a deflated tyre

[GroundEffect]

Rolling resistance comes from the deformation of the tyre as it rolls - that's where the energy goes. Anything you can do to stop that, reduces it.

There is also some chemical 'adhesion' involved too with really stick racing rubber.

[HertsBiker]

Complying to a bump is good though, so an overly stiff side wall causes the suspension to rise, possibly the whole car. This also costs energy! It's not as easy to define as 'firmer is better'. My mondeo is more economical at 32 psi than 36....

[yzrh]

I think if your tyres are at high pressure and your suspension very stiff you will have the lowest rolling resistance

[HertsBiker]

yzrh said:

I think if your tyres are at high pressure and your suspension very stiff you will have the lowest rolling resistance

How? If you hit a bump the whole car will rise. Which slows you down. Which equals more fuel. Does your reply still hold water?

[yzrh]

HertsBiker said:

How? If you hit a bump the whole car will rise. Which slows you down. Which equals more fuel. Does your reply still hold water?

It does unless you are proposing that the road will have bumps more often than not, which is nigh on impossible unless you are driving off road.

In that case then lower pressure tires are required.

[yzrh]

And also bear in mind that a high pressure tyre will make less contact around the bump than a lower pressure tyre, which reduces the friction and goes some way towards mitigating the extra energy to lift up the car by a couple mm.

[Qwert1e]

yzrh said:

I think if your tyres are at high pressure and your suspension very stiff you will have the lowest rolling resistance

..and the worst braking!

[yzrh]

Qwert1e said:

..and the worst braking!

Of course