MikeG.
Established Member
Schultzy,
Rubber might expand, but within quite small tolerances steel doesn't. Tyres are made of steel and rubber. Watch a flat tyre as it is inflated.......better still, put a dressmakers tape around it............the distance from the ground to the axle will certainly change, but the circumference will not. A flat tyre bulges out at the sides. The fact that the distance from the ground to the axle changes as you inflate the tyre you have observed....but you haven't mentioned that the distance from the axle to the top of the tyre does not expand. That would be a pre-requisite for an expansion of the circumference.
Someone on here is going to have to do a trial of this!! Remember, it must be a car tyre.......not a bike tyre or wheel barrow tyre (which are all rubber).
Anyway, this isn't my theory. If you check the tyre section of "Vehicle Dependent Expedition Guide" by Tom Shepherd....(who was Land Rovers main expedition man and wrote a number of instruction books on highly technical stuff for them), you will see where I first read this fact.
It was an important fact for me, because I had to navigate across the Sahara by dead reckoning (at times) with tyres deflated to ease sand-driving. I had to know what my mileage was exactly, and calibrated the speed through numerous tests. Tom Shepherd then confirmed this counter-intuitive fact for me, and my thousands of miles of checking as I crossed Africa proved him exactly right.
Mike
Oh..the dragster thing. They are clearly one or two use tyres.....I can't imagine they are made in the same way as car tyres . I don't suppose there is much steel in them, because that circumferential expansion seems to be something they actively seek...........not a trait that is very useful in a Fiesta tyre!
Rubber might expand, but within quite small tolerances steel doesn't. Tyres are made of steel and rubber. Watch a flat tyre as it is inflated.......better still, put a dressmakers tape around it............the distance from the ground to the axle will certainly change, but the circumference will not. A flat tyre bulges out at the sides. The fact that the distance from the ground to the axle changes as you inflate the tyre you have observed....but you haven't mentioned that the distance from the axle to the top of the tyre does not expand. That would be a pre-requisite for an expansion of the circumference.
Someone on here is going to have to do a trial of this!! Remember, it must be a car tyre.......not a bike tyre or wheel barrow tyre (which are all rubber).
Anyway, this isn't my theory. If you check the tyre section of "Vehicle Dependent Expedition Guide" by Tom Shepherd....(who was Land Rovers main expedition man and wrote a number of instruction books on highly technical stuff for them), you will see where I first read this fact.
It was an important fact for me, because I had to navigate across the Sahara by dead reckoning (at times) with tyres deflated to ease sand-driving. I had to know what my mileage was exactly, and calibrated the speed through numerous tests. Tom Shepherd then confirmed this counter-intuitive fact for me, and my thousands of miles of checking as I crossed Africa proved him exactly right.
Mike
Oh..the dragster thing. They are clearly one or two use tyres.....I can't imagine they are made in the same way as car tyres . I don't suppose there is much steel in them, because that circumferential expansion seems to be something they actively seek...........not a trait that is very useful in a Fiesta tyre!
