Why can't bike tyres be like car tyres?

[Davidc]

I know that bike tyres operate at higher pressures, but why is it that car tyres can stay at the right pressure for months, but my bike ones can only manage a week or so?

The pressure in my mtb tyres isn't very much higher than in the car ones, but they need pumping up once a week!

On the tourer (presta valves) with tyres at much higher pressures its about two weeks.

 

[Pottsy]

At a guess I'd say the much much greater volume of air in a car tyre means a little leakage makes comparatively very little difference to the overall pressure.

Secondly, personally my bike tyres are at a much greater pressure than my car tyres (say 100psi versus 30psi), which should encourage more leakage too I suspect.

 

[orienteer]

Car tyres are tubeless. Inner tubes are thin and slightly porous.

 

[GrasB]

Car tyres lose about the same volume of air a day as bike tyres. Thing is it takes about 20 strokes of the pump to get from 0 to 110 psi on my road bike, that's about 0.75psi worth of air in the Alfa's tyres.

 

[dubman]

Ive not had to do mine on new bike with presta valves for couple months now , have checked the pressure and they havn't lost any , my other bike on schrader valves needs doing every 2 weeks or so.

 

[hubgearfreak]

they're thicker, and by a lot.
you could have bicycle tyres with 6 or 10mm wall thickness, but they'd sap some energy

 

[beanzontoast]

IME, bike tyres are getting too much like car tyres - they cost about the same

 

[Davidc]

Thanks for those - I suppose most of the reasons are logical.

I was very p'd off with my bike tyres when I posted that. I'd checked the car ones and no need to do anything after about 4 weeks of neglect, but had to pump up the bike ones yet again after a week and two weeks (shraeder mtb and presta tourer).

 

[mr-marty-martin]

inner tubes dont loose much air at all ive found, well i never feel they go down even after time

but tubular tyres do, with their latex inner tubes

 

[Will1985]

Has anybody tried tubeless bike wheels yet? It would be interesting to see a direct comparison. The thickness of the rubber must have a lot to do with it.

 

[tyred]

I don't see that tube/tubeless has anything to do with it. I would go with the volume of air thing. Tractor tyres have tubes and usually stay at the same pressure for 20+ years but they hold a lot of air.