Those look like reasonably old bikes. The brakes are likely to have a lot more clearance than most modern sidepulls. But clearance is going to be your limiting factor. I would try and borrow someones wheels/tyres and have a go at fitting them. The places to watch are normally the brakes, the fork, and the chainstays.
Remember to check what size wheels you have. You might well have 27" wheels, which would limit you tyre choices quite a lot.
Good luck. I hope you give it a go!