UKC

I need some new Gatorskin road tyres. I can't find the size marked anywhere on the old ones. I'm thinking they are 700c 25's. Is there any sure way of finding out?

One of these may help https://www.screwfix.com/p/magnusson-vernier-callipers-6-150mm-/4269V?tc=MB... 

700c 25 would be pretty normal for a road bike.  Depending on the fork clearance (how old is the bike ?) Then fitting 28s wouldn't be a bad move.

It seems 28mm with lower pressures are the future. Take a bit of a leap of faith but I'm finding my new set-up very good.🚴🏻‍♂️

I agree on 28s, but my older bike doesn't have fork clearance above 25.

Mmmmm....16 year old carbon bike. Yes, I think that's the size. Just surprised it's not printed on the tyre. I'll think on idea of 28's. Thanks.

Quite probably 700x23c on a bike that old.

You might just about get away with 25, but 28 would be too big, I think.

The size is on the sidewall but it is always a bit hard to make out

Thanks. I got 700 × 25's. I'll report back when fitted. I've looked really carefully on sidewalls and can't see any evidence of info. The new ones are clearly marked.

Yep, 700 × 25 have gone on fine. They look good. I ordered them online 2pm Sat, they arrived 12.15pm today, freepost.