Please could someone do a masterclass on tyres, and even better if they could do it in a  YouTube video.

I have always found the specifications of tyres very confusing.

On Jim Tanner';s advice I bought pit bike wheels which are M2R KMX-R 160 Pit Bike Front 17" Rim. I saw some he brought to Gaydon and really liked them. They look solid with thick spokes.

But once you have wheels of whatever rim size, as long as you get the right diameter, do they expand to fit the rim? I mean, does the 160 become irrelevant, with air pushing the tyre rim out?

How do the proportions and %s of tyre dimensions work, etc?

When it comes to fitting them there’s lots and of tutorials on YouTube.   And there’s no way I can say this without encouraging sniggering from the back of class,  but I found tyre lube helped alot.

A range of tyre widths will fit the rim - depends a bit on the rim but mainly the tyre.   You’ll find lists online showing typical ranges.   For reference I have used 2.5” upto 3.25” on a pit bike wheel similar to yours without problem.

cheers

as regards the 3.25", I asked Jim this and I think he said that it is not just the size of the wall - something about proportions

incidentally, I confess to not even understanding what the 140 or 160 mean. I assumed mm, but of course that is ridiculous

The pit bike wheels going on my new contraption kart thingy are 1.6 inches between the flanges on the rim. I chose that width so I can fit 3.25 17 Avon ditch finders. Listed as safety milage for some reason. They have a flat top and
are quite vintage looking. Pricey for new but can picked up at auto jumbles.

The pit bike wheels going on my new contraption kart thingy are 1.6 inches between the flanges on the rim. I chose that width so I can fit 3.25 17 Avon ditch finders. Listed as safety milage for some reason. They have a flat top and
are quite vintage looking. Pricey for new but can picked up at auto jumbles.

ditch finders? Not heard that before. What do Avon call them?

Flat topped and vintage sounds good

To check sizes, try
http://www.bits4motorbikes.co.uk/tiresizeconversion.html

great! thanks

and the ability to carry 900 odd pounds.