wheel math ?

[TwoSeven]

Does anyone know how to calculate the radius of a wheel+tire at the tires outside edge. I can do it on the center of the tire, but I need to know what it is on the outside edge of the tire.


Cheers

[Brian d marge]

Does anyone know how to calculate the radius of a wheel+tire at the tires outside edge. I can do it on the center of the tire, but I need to know what it is on the outside edge of the tire.


Cheers

I ll pm you about this ... ya have to take into concideration ,,wind velocity and Chicken or beef in the case of Vindaloo ( which will have a bearing on weight, which will affect the radi )

Styphen

[TonyB]

As I understand it, the aspect ratio will give you the answer. If you have a 180/55 17 then the height of the tyre above 17" is 55% of 180mm, or 99mm.

[cowpoos]

spirit level and some vernier calpiers....

[slopster]

draw a mark on the bottom of the tyre and the ground next to it. Roll the bike foward till you mark touches the ground again. Measure the distance between those points and divide by 3.14 for diameter. Halve that for radius.

[merv]

You are asking a tricky question because you are wanting to do it on the outside edge, presumably at maximum lean angle. What do you want to know that for anyway? It won't be significantly different to the centre of the tyre if the shape of your tyre is kinda on the line like an arc from the centre of the hub.

Somehow then you've got to measure to that edge of the tyre and the measurement will vary depending on how curved the tyre tread is i.e. some tyres are kinda square, some wrap around a lot. Maybe you need some sort of measuring wheel that you can hold against the edge of the tyre as you spin the wheel. You could do the old move the bike along the ground trick which you'd have to do with it leaning over and going around a curve and you'd have to mark the curve it took so you can measure the true distance on the ground, hence suggesting the measuring wheel as I think that would be easier.

[Pixie]

If it's the radius at the edge you want?
Use a bloody tape measure.
Measure from the axle's surface to the edge of the tyre,then add half the axle's diameter to the result.

[Hitcher]

Does anyone know how to calculate the radius of a wheel+tire at the tires outside edge. I can do it on the center of the tire, but I need to know what it is on the outside edge of the tire.

It shouldn't require a "colonial" to remind you that these are tyres. I'm tired now. I should have a lie down.

[Brian d marge]

It shouldn't require a "colonial" to remind you that these are tyres. I'm tired now. I should have a lie down.

the word Tire comes from attire so the correct spelling is tire ..

Stephen

[Hitcher]

the word Tire comes from attire so the correct spelling is tire

Not according to the Oxford English Dictionary:

[A variant spelling of TIRE n.2, both being used indifferently in 15th and 16th c. In 17th c. tire became the settled spelling, and has so continued in U.S.; but in Gt. Britain tyre has been revived for the pneumatic tires of bicycles, carriages, and motor-cars, and is also sometimes used for iron or steel tires.]

1. The iron or steel rim of a wheel, esp. the steel rim of the driving wheel of a locomotive: = TIRE n.2 2a.

1796 W. FELTON Carriages Gloss., Tyre, the iron which rims the wheels. 1801 Ibid. II. 13 Extras to Wheels. Hooped tyre. Patent ditto. 1825 J. NICHOLSON Operat. Mechanic 647 The advantage of hooping cast iron wheels with malleable iron tyres or trods. 1838 BOURNE & BARTLEY Patent Specif. No. 7795, 6 Sept. 3 The felloe turned..to receive an ordinary outside hoop or tyre. 1862 SMILES Engineers III. 365 There are limits to the strength of iron,..and there is a point at which both rails and tyres must break. 1865 Athenæum 30 Sept. 442/1 Prior to the invention of weldless tyres. 1889 G. FINDLAY Eng. Railway 130 A steel tyre, spun from a solid block of Bessemer steel, without a weld.
2. a. A rubber cushion around the wheel of a bicycle, motor-car, etc.: = TIRE n.2 2b.

1875 Encycl. Brit. III. 665/1 India-rubber tyres..were brought into requisition to relieve jolting. 1890 Patent Specif. No. 4206 Large rubber tyres..known commercially as (1) Pneumatic tyres, (2) Cushion tyres. 1891-1898 [see PNEUMATIC 1b]. 1902 Encycl. Brit. XXVII. 325/1 In 1846 Mr. William Thompson had taken out a patent for a pneumatic tyre for carriages.

[Brian d marge]

Tom french tire technology 1989 .... The name is derived from attire -a protective covering or coat; in this sense the american spelling tire is closer to the original than the british tyre ( a tire is still called a cover in the rubber industry )

un snip

That was from the gold wing owners club ..which as you are aware, is a much more useful reference than the oxford ..


Stephen

[TwoSeven]

As I understand it, the aspect ratio will give you the answer. If you have a 180/55 17 then the height of the tyre above 17" is 55% of 180mm, or 99mm.

Nope - thats the centre height of the tire - I need outside height.

From what I have found out so far I need to get a profile guage and measure the buggers - or phone the tire folks up and ask their sidewall heights. I dont want to have to measure tires every time I want to buys some, but looks like I'm going to have to. So excuse me if you see a strange person walking around bikes measuring wheels

Tire is the correct word - however, me being english, whatever word I use will be the correct.

[MSTRS:Me]

What is wrong with 2piR (2 x 3.14 x radius) ?

[merv]

You still haven't told us why do you need this outside tyre height?

The only other way is find someone with a huge caliper set that will fit from the outer edge of the tyre at the top to the diagonally opposite edge at the bottom. Any other means except measuring circumference like most of us described will be a problem e.g. what use is a tape measure trying to measure around corners to get to the tyre edge?

[cowpoos]

ya pretty thick for a so called clever guy arn't ya