Why are Tyre sizes a mixture of Inches and mm

[Guest]

OK so why are the rims in inches when everything else on the bike is metric

My speedo reads in miles an hour

[CrusaderPhil]

OK so why are the rims in inches when everything else on the bike is metric

My speedo reads in miles an hour

 

Ah! that might explain it, inches are a fraction of mile and the distance for one revolution i.e. the circumference would also be a proportion of a mile but then the profile which on a 160/60 is 60% of 160mm so that blows that theory out of the water.

[CrusaderPhil]

OK so why are the rims in inches when everything else on the bike is metric

My speedo reads in miles an hour

 

Ah! that might explain it, inches are a fraction of mile and the distance for one revolution i.e. the circumference would also be a proportion of a mile but then the profile which on a 160/60 is 60% of 160mm blows that theory out of the water.

[someone]

OK so why are the rims in inches when everything else on the bike is metric

 

For the reason I said in the post you quoted.

Changing wheel sizes causes a lot of hassle and cost that is just not worth it. You cannot simply switch an 18" wheel (457.2mm) for a 450mm or 460mm one without other changes to a bike's design. And introducing whole new rim sizes would also mean needing whole new range of tyres for them, as none would previously exist. It is just not worth changing just for the sake of it.

But tyres do not have to be so exact. My rear wheel takes an 3.50x16 (imperial) or 100/90 16 (metric) tyre. But a 3.50" width is 88.9mm, and an 100mm width is 3.94".

[TimR]

And why is it ..virtually all hgvs over 10ft high have their height recorded in cab in feet and inches...

All bridges in the uk are marked out in feet and inches (some with metric also)

BUT virtually all garage forecourt canopies are marked in metres ..... ...

[CrusaderPhil]

OK so why are the rims in inches when everything else on the bike is metric

 

For the reason I said in the post you quoted.

Changing wheel sizes causes a lot of hassle and cost that is just not worth it. You cannot simply switch an 18" wheel (457.2mm) for a 450mm or 460mm one without other changes to a bike's design. And introducing whole new rim sizes would also mean needing whole new range of tyres for them, as none would previously exist. It is just not worth changing just for the sake of it.

But tyres do not have to be so exact. My rear wheel takes an 3.50x16 (imperial) or 100/90 16 (metric) tyre. But a 3.50" width is 88.9mm, and an 100mm width is 3.94".

 

My wheels are supposed to be 17" but they are not.

[Guest]

My wheels are supposed to be 17" but they are not.

are they 19" then?

[JRH]

And why is it ..virtually all hgvs over 10ft high have their height recorded in cab in feet and inches...

All bridges in the uk are marked out in feet and inches (some with metric also)

BUT virtually all garage forecourt canopies are marked in metres ..... ...

Because fuel is sold in litres.