Please could I have a recommendation for a 'true 28' tyre to mount on an Open Pro
No. If you want 28mm tyres, you also want rims wider than Open Pro.
Oh, alright then, try Vittoria Rubino Pro Tech, they have a good mix of attributes at a low price, and they are a bit under 28mm on skinny rims.
If you want to spend twice as much, I expect Open Pave Evo CG III 700×27 is probably 28mm, based on the way the 23 and 25 come up slightly over the spec size.
No. If you want 28mm tyres, you also want rims wider than Open Pro.
Oh, alright then, try Vittoria Rubino Pro Tech, they have a good mix of attributes at a low price, and they are a bit under 28mm on skinny rims.
If you want to spend twice as much, I expect Open Pave Evo CG III 700×27 is probably 28mm, based on the way the 23 and 25 come up slightly over the spec size.