Rear tyre on a '70 to '73 bike ?

[Grewth]

Will a 120/90H18 Cheng Shin fit OK on a XS1 ?
Seems very wide for the swing arm clearance at the moment (132mm) but it's loose not fitted, fitting to the rim may actually pull it in a little.
I really don't want to fit it tomorrow morning only to have to pull it off again.
The only other tyre I've got is a Czech Barum 4.00x18 which is narrower and 100% aspect ratio, but I know these are terrible things to a 1950's design.
I put a new one on my Honda CB550F, and it destroyed the casing in 6,000 miles

 

[GLJ]

I had a Continental GO 120/90-18 on the rear of my XS2 a couple of years ago. It fit but was a very tight fit. Right now I'm using a 110/90-18 a lot more room.

 

[Grewth]

Many Thanks.
I know it might sound like a daft thing to ask about, because of course everyone knows that a 120/90 tyre is 120mm wide.
But that is a NOMINAL figure.
Experience has taught me that no two tyres from different manufacturers are EXACTLY the same size.
They will vary in height and width by a few mm.
I'll take a risk and fit it tomorrow, and see how it goes.

 

[wesleyonoel]

Just installed a 110/90 X 18 Durotour tire on the rear of my '73 TX. Was a bit concerned as width measured a bit wider than original 4.00X18 tire but it fit well..

 

[Grewth]

Changed my mind and fitted the Barum 4.00x18 instead.
Simply because it's 100% aspect ratio making it quite a tall tyre, and I still have to fabricate a centre stand for my XS1B project.
I also fitted a 3.25x19 Mitas on the front wheel, again 100% aspect ratio because I've got to fabricate a mudguard yet, if it clears that tall Mitas, it will clear everything else.
Then I found out that they are only P rated for speed - that's just 93 mph.
Damn