Tyre Pressures

[abo]

My Conti Double Fighters have a max pressure of 65psi according to the text on the tyre. If I went higher than this what would be the pros and cons? They're currently sat at 64psi, but I just got to wondering as I was checking the pressures...

 

[Paulus]

A couple of pound over the top won't cause any problems, but, go too much over and the tyre will wear quickly as the centre of the tread will be pushed upwards, also there could be a possibility of the tyre blowing off of the rim.

 

[HLaB]

I doubt there would be much benefit in going higher than the max, having them at pressure is a good thing, you'll get less p'tures and they'll roll better, if they are too high the ride will get harsher and worse the tyres could blow of the rim.

 

[Bicycle]

I'd be wary.

A few years ago I put slick Conti SportContacts on an HT MTB to turn it into an traffic-buster missile for urban commutes.

I think the max psi was 80, but I went to 95 to minimise rolling resistance.

It was absolute mustard to ride on the road with the forks locked out, but it punctured every time a nearby sparrow broke wind.

More fun to ride them at 95 psi, but more sense to do so at 80 - and they still let me move along at a decent clip.

Before that I hadn't taken the Max Pressure advice seriously. After my experiment and much puncture repairing, I do.

I hope this helps.

 

[abo]

Thanks guys! Yeah, I was thinking about punctures but hadn't considered the tyre blowing off the rim I'll be keeping them where they are for sure, but you know how you get to thinking about these things lol

Speaking of tyre wear I notice the rear now has a lovely flat spot, I presume I picked it up yesterday following a slide when some bellend in a gold Rover 75 (on the phone too...) turned in front of me at crossroads. Thanks, moron.

 

[Angelfishsolo]

Rule of thumb the greater the pressure the greater the wear on the centre of the tyre and also the least rolling resistance. Lower pressure means a more equal wear patter and greater rolling resistance. As has been said a few PSI over will do no harm but if you went maybe 10psi over you would run the risk of a blow out and also have an extremely uncomfortable ride. As for running below recommend the again a few psi will make no odds but much lower will result in danger to the rims and pinch flats.

 

[Angelfishsolo]

Some advocate swapping front and rear tyres after a while so you have the greatest tread of rubber (n case of slicks) on the drive wheel. If the bald patch is serious then maybe a new tyre is in order?

Thanks guys! Yeah, I was thinking about punctures but hadn't considered the tyre blowing off the rim I'll be keeping them where they are for sure, but you know how you get to thinking about these things lol

Speaking of tyre wear I notice the rear now has a lovely flat spot, I presume I picked it up yesterday following a slide when some bellend in a gold Rover 75 (on the phone too...) turned in front of me at crossroads. Thanks, moron.

 

[Angelfishsolo]

Sometimes life is a far better teacher than printed literature

I'd be wary.

A few years ago I put slick Conti SportContacts on an HT MTB to turn it into an traffic-buster missile for urban commutes.

I think the max psi was 80, but I went to 95 to minimise rolling resistance.

It was absolute mustard to ride on the road with the forks locked out, but it punctured every time a nearby sparrow broke wind.

More fun to ride them at 95 psi, but more sense to do so at 80 - and they still let me move along at a decent clip.

Before that I hadn't taken the Max Pressure advice seriously. After my experiment and much puncture repairing, I do.

I hope this helps.

 

[abo]

Yeah, the other thing is, I chose these tyres because I like to mix it up between roads, cycle track, (steps ), and trails which can be gravelly. I don't think I'd like to be running massive pressures on jagged gravel...

 

[Angelfishsolo]

Er no, not a great idea (voice of past experience echos in my head )

Yeah, the other thing is, I chose these tyres because I like to mix it up between roads, cycle track, (steps ), and trails which can be gravelly. I don't think I'd like to be running massive pressures on jagged gravel...

 

[blockend]

Rule of thumb the greater the pressure the greater the wear on the centre of the tyre and also the least rolling resistance.

That's not quite correct in real life. When a bike has a human body to power it the least rolling resistance is the tyre pressure which allows the rider to maintain progress on a given surface. If your roads are uneven, 70psi might be the optimum, if you ride in post apocalyptic urban ghettos with zero highway maintenance, 50psi in a 1.5" cover could be plenty air.

A 120psi 23mm tyre will deflect over the smallest stone, thus increasing rolling resistance, which will then be passed onto the rider's wrists and backside, leading to fatigue.

 

[Angelfishsolo]

OK that is a valid point and I stand corrected.

That's not quite correct in real life. When a bike has a human body to power it the least rolling resistance is the tyre pressure which allows the rider to maintain progress on a given surface. If your roads are uneven, 70psi might be the optimum, if you ride in post apocalyptic urban ghettos with zero highway maintenance, 50psi in a 1.5" cover could be plenty air.

A 120psi 23mm tyre will deflect over the smallest stone with minimal deflection, thus increasing rolling resistance, which will then be passed onto the rider's wrists and backside, leading to fatigue.

 

[Kestevan]

Some advocate swapping front and rear tyres after a while so you have the greatest tread of rubber (n case of slicks) on the drive wheel. If the bald patch is serious then maybe a new tyre is in order?

I wouldnt... the rear may wear more quickly than the front but the best tyre should always be up front.
A blowout on the rear wheel will probably allow you to bring the bike to a safe and controlled stop. A similar incident on the front and you'll either be picking bits of your teeth out of the tarmac, or detaching your testicles from behind your ears.... neither is pleasant.

 

[abo]

Some advocate swapping front and rear tyres after a while so you have the greatest tread of rubber (n case of slicks) on the drive wheel. If the bald patch is serious then maybe a new tyre is in order?

I wouldnt... the rear may wear more quickly than the front but the best tyre should always be up front.
A blowout on the rear wheel will probably allow you to bring the bike to a safe and controlled stop. A similar incident on the front and you'll either be picking bits of your teeth out of the tarmac, or detaching your testicles from behind your ears.... neither is pleasant.

Its only a small patch, you can see about an inch wide by maybe 1.5 inch along the circumference of the tyre. It has basically rubbed down the little tread blocks a bit, not quite a slick spot. The shoulder knobbles are intact.

Thanks for that bit of advice btw, I don't fancy a blowout induced handlebar vault