Tyre Sizes

[charlie]

Many of the tyres on our old machines have two sizes on them, this can cause confusion. So what do they mean?
Taking the tyres on a Monro Tiller as an example, they are marked 3.00 – 6 with 12×3 also appearing. 3.00 is the rim width and 6 is the wheel diameter. 12 is the overall diameter of the tyre and 3 is the width of the tyre.
3.00-6 in modern metric size is equivalent to 75/100R6, where 100 is the cross section ratio of tyre height and width.
I hope I have got this right and it is of some help.

[charlie]

Just had a thought. It might be a good idea to build a list of machines and what size tyres they use. This would give a better idea of how common or not each size is and where tyres are interchangeable. To make a start I have listed a couple on the attached.

Attachments:

1. Tyre-Sizes-chart.doc

[will-haggle]

When I bought my Anzani Motor Hoe, the tyre size was 12½ x 2¼”, I wondered where to get some. 2.25 x 8 is the rim size and looking around the web they were readily available! I am a voluntary bicycle mechanic at the Bikes For Africa charity and we were scrapping a lot of small childrens bikes, I found one with the right tyres (black ones with a fairly chunky tread) and for a donation, got them. I sold the Anzani and the tyres and tubes to go with it…

Attachments:

1. 

[oddhatuk]

This I think is a good explanation of tyre sizes

http://www.allterraintyres.co.uk/index.php?main_page=page&id=8

All Terrain Tyres is an offshoot of Tyre Rite.

[charlie]

Hugh that is an excellent link, covers just about every way tyre sizes have been and are given.

[charlie]

Added a couple more to the list, if you have others to add please let me know.

Attachments:

1. Tyre-Sizes-chart1.doc

[will-haggle]

Hey Charlie, with a few more additions this will be a good filler for the Cultivator, I know a few more!

[oddhatuk]

Thanks Charlie,

Your list will be a very useful reference, perhaps there should be a section on the forum for info such as this.

My Ransome C29 tool frame had 10 x 2 Dunlop tyres on the depth wheels, I think this is 4.00 – 6 in modern terms

[charlie]

Alan, I was thinking the same, it will get the information to all members and hopefully prompt a few to add other sizes to give a more complete picture. Something that would be useful is an additional column with the modern equivalent size if available.
Hugh 10×2 would be overall tyre diameter and width, 4.00-6 would be rim width and wheel diameter, so not sure it is correct, 2.00-6 would be more likely.

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