[Tyre size GSX750 1981]

Can I just check this is a suitable rear tire - check out the link 

 

https://se.mynetmoto.com/shop.cfm/mnm000005968/continental-120-90--18-(65h)-conti-go!.html

[Tyre size GSX750 1981]

Thanks for the input guys ! I found a manual and it corresponds with what you said so I guess I can't go wrong if I go get tyres at those specs ! Thanks 

[Tyre size GSX750 1981]

Hi 

I just acquired a 1981 GSX 750 - cannot for the life of me make out the tyre sizes - tyres probably original as it was a barn find and the sidewalls are worn down from being flat I guess - were they just standard tyre sizes on these that someone will know or were there variants ? 
thanks in advance