I was surprised at the range of widths that will fit on a given rim.  Andy Boulton was/is selling tyres for a good price.   From memory they are 2.1" which would fit both those sets of rims.   Others have more experience on the C90 wheels, but I've run 2.5" up to 3.25" on my pit bike rims which are nominally 1.6 or 1.8 I think.

Yes I have experimented quite a lot with rims and tyres on the c90. As you say Stefan, you can get quite a variety of tyres to fit the 1.40 rims which is what my karts generally run so up to 2.75 is ok. On my rims that were 1.60 I was able to run up to 4" but they had limited performance capabilities but looked cool.

I will be trying some 1.85 rims with 3" Heidenau tyres on which are a nice block pattern and should perform ok as very low profile.

I have got tyres from Demon tweaks, My tyres, wemoto and from people selling parts for custom honda cubs on Facebook groups etc.

The prices soon add up though and I guess it depends what you are after, If i am honest i have not found much performance differences just I am trying to achieve a look at the same time.

For those who have single wheel braking - my advice is to buy 5 tyres!!!! as you will go through them and if you wait you can bet they won't have them again when you just want to buy one!!

 

Not sure you'll find a consensus on size as it's a bit of a balance between the look (wider) and handling.     I started with 3.25" on the Bugatti and now run 2.75" and it handles better and I saved a ton of weight.   I suspect 2.5 would help the tail break away a little easier when I run the rear axle with both wheels keyed, but mostly I use one freewheel so stick with the 2.75s.

A flatter profile tyre would give more of a period look but they're tricky to find.   Austin 7's or sidecars would be places to look but the tyres would be very heavy.  I asked Longstone tyres and they couldn't suggest anything.

I wouldn't worry too much about wear.  If they do wear out in a season, you'll be smiling so much you won't care!