Tyre clearance measurements.

Pirelli Cinturato Gravel H 35mm mounted to 30mm wide (24mm internal) rims = measured width 36mm
Driveside clearance = ~12mm
Non-driveside clearance = ~10mm

So say roughly 20mm additional width available - 4mm minimum clearance each side (8mm total) = additional 12mm available
36mm + 12mm = approx. maximum 48mm clearance or conservatively 45mm.

This doesn’t account for any reduced clearance due to front derailleur. I haven’t mounted it yet but 105 di2 front derailleur doesn’t look like it will be a problem.

I will upload some photos when I have a chance.

Looks like my earlier tape measurements were taken too close to the seat tube and I should have bought larger tyres!

Looking to buy one of these frames and use 40mm tires with a di2 setup like yours, what is the tire clearance like with an di2 front mech? Is it limited at all by the front mech? Thanks in advance