High Tire Pressure

I called the dealer and he said that they are over inflated at the factory which makes them easier to move around.
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That's a load of bull, but it made you happy and got you off the phone, so I suppose it worked. :-)

While it is usually necessary to greatly over inflate tires to seat them onto the rims, they are never supposed to be left at such dangerous pressures...unless somebody screws up, or has a seriously malfunctioning air guage! HAHA!! :-)

I happened to check my tires after a 20 mile ride. They were at 47 PSI coming in hot.
Stone cold at 41 PSI a few hours later.

Is that about the normal high PSI pressure when they are hot? What are you guys seeing?

I happened to check my tires after a 20 mile ride. They were at 47 PSI coming in hot.
Stone cold at 41 PSI a few hours later.

Is that about the normal high PSI pressure when they are hot? What are you guys seeing?

You should only take the tyre pressures when the tyres are cold.

I happened to check my tires after a 20 mile ride. They were at 47 PSI coming in hot.
Stone cold at 41 PSI a few hours later.

Is that about the normal high PSI pressure when they are hot? What are you guys seeing?

I have not tried it out but will do.
I often wondered what you are supposed to do when you find you tyres are flattish whilst you are out and about riding. Sometimes you cannot wait until they are cold to inflate them, so it would be good to know what pressure is right when they are hot.

I happened to check my tires after a 20 mile ride. They were at 47 PSI coming in hot.
Stone cold at 41 PSI a few hours later.

Is that about the normal high PSI pressure when they are hot? What are you guys seeing?

I have not tried it out but will do.
I often wondered what you are supposed to do when you find you tyres are flattish whilst you are out and about riding. Sometimes you cannot wait until they are cold to inflate them, so it would be good to know what pressure is right when they are hot.

That is a good point. If you check the tire pressure while hot and even then it is below 40 PSI, what do you inflate it to?
I think if I was riding and happened to check while hot, I would only inflate it to 40 PSI just till I could get home.

Generally the advice would be to inflate to the specified tyre pressures even if hot, and then as Morrison wrote above to recheck them again when cold.

If I find myself in that situation I normally pop in another 4PSI over the specified, this will bring the pressure to close where it will be when hot anyway, not exactly, just close to. That will help prevent riding on under-inflated tyres which may cause you battery life issues on that particular journey, the extra drag of an under-inflated tyre causing more load and hence quicker discharge.

But its all horses for courses whether you do this or not. The critical thing is to re-check those pressures when the tyres are cold again *without fail*.

As long as you don't exceed the maximum pressure on the sidewall you should be good. Most tire failures are from under inflation. The 4 psi plus is a good idea, my car has a tire pressure display and the average change from cold to hot is 4 psi.

Philip

I don't understand the logic of this. If a tyre/tire is overinflated by 4psi when cold, then with running it will then be 8psi (approx) over the expected running pressure.

Most tires should be able to stand 10 percent or so over the pressure shown on the sidewall - and it reduces rolling resistance and range per charge.

I have kept my 47 psi (325 kPa) Pirelli SL-26 tires about 10% overinflated most of the time, and the only effect is the a bit harder ride and the tread wear at the tire centerline is accelerated. Obviously, the possibility of skidding in some situations probably increases with less tire contact with the road and with increased tire-bouncing on bumpy surfaces, so I must ride a bit more conservatively.

Raymond,

Recommended pressures are based on the tyre being cold (UK spelling fine with me). The increase with temperature rise is "figured into" the recommended cold pressure. The specific temperature when cold isn't important, since the temperature rise will be about the same on a cold day as a warm day.

But come to think of it, a hub-motored scooter does add additional heat to the rear tyre that is not considered by the tyre manufacturer. but there is a lot of conservatism in the structural design of tyres and excess pressure is almost unheard of source of in-service failure.

There are a couple dramatic exceptions - never weld on a tyre rim with the tyre mounted and inflated - this kills a few people on the job here in the US every year - the most peculiar aspect of such accidents being a runaway pressure increase that doesn't start until several minutes after the welding is done and the worker thinks he is safe. A similar thing can also happen when a truck-mounted crane contacts high voltage power lines - the exploding tyres, are as big a danger as the electricity. It also happened once to the tyres on one of those huge end-dump trucks at an Australian strip mine when the truck was struck by lightning, like the welding incidents, there was a long delay before the explosion.

a hub-motored scooter does add additional heat to the rear tyre that is not considered by the tyre manufacturer.

Are you sure about that?

I used to ride a shaft-drive cruiser bike, and the rear hub would get too hot to put your hands on. I'll admit, I haven't bonded well enough with my Vectrix to get on the ground and hug the rear end after a ride, but does the motorhub really get THAT hot? And if so, how much of that heat is actually transferred through the gearbox to the rim and tire? I just don't see that being an issue at all.

On the other hand, consistant use of the regen braking system puts perhaps a little more tread stress on the tire than normal motorcycle dual wheel braking, but since many riders gear down to slow down, I wouldn't think there'd be enough difference there to show up anyway.

My normal daily Vectrix routine would be impossible to measure range differences from one day to the next, because every day, the traffic is different, some lights catch me and some don't, some days are colder than others, etc. There's no way I could ever determine an actual range change with a pound or two of air pressure. Just too many other variables involved. So, I just check the tires once in a while and fill them up to spects and forget it.

I don't understand the logic of this. If a tyre/tire is overinflated by 4psi when cold, then with running it will then be 8psi (approx) over the expected running pressure.

No, the advice I gave was to add 4psi to a warm/hot tyre if you have to inflate or add pressure when out and about. Then as the tyre cools to ambient temperature you should see the pressure drop to the 40psi (rear) or 32psi (front) that it is supposed to be.

This advice is given strictly as a get-you-there measure rather than being something you should do as a natural course of things. It is wise to stick to the manufacturers specifications. Should something bad happen the last thing you want is for the fault to be at your own hands!

Remember, when the tyres are once again "cold" you should check and adjust them to the manufacturers specifications.