Tire width for Pacenti SL23 rims + Parlee Altum R frame?

[danbeam]

Hey all,

I have a Parlee Altum R frame that I'm about to build up, and a new set of wheels with Pacenti SL23 v2 rims (20.3mm internal width, 24.3mm external). I like Continental GP4000S tires, and am probably gonna run the wheels as clinchers for now.

My question: which tire width should go for?

I've heard:
a) 23s work well aerodynamically with my rims
b) wider == more comfortable
c) SL23 rims expand the effective width of my tire (so it'd add 2-4mm)

My frame says it can clear 28mm tires[1], but putting 28s on wide rims might not be what they envisioned. My friend has the same sized Altum (not R) and has had rubbing issues with his wide rims and (I think?) 28mm tires.

[1] http://www.parleecycles.com/altumr-feature-tour/

[eBAUMANN]

it'll probably clear 25c gp4ks. they get big on a wide rim but fit in an enve fork, which means unless that frame was designed by a bunch of wankers, it should fit in the rear as well.