622-32 on a MA40?
 

Good morning BF vintage experts. Anyone got real life experience using wider tyres on Mavic MA40s?
I've set up an old Shogun as a tourer, and am looking for something meatier than the usual 622-23s to cushion the bumps.
I'm thinking of trying 32 profile tyres. The MA40s rims have an inner width of 13.5mm. Sheldon Brown says I shouldn't go bigger than a 25, so I know the theory.
I wonder if anyone has had actual experience doing something similar? Keen to hear, thanks.

I have been using dimensionally identical Mavic MA-2s on my Mercian Vincitore for nearly 18 years with nominally 28 mm tires with no issues. This includes Continentals that were actually around 26 mm and Paselas that actually ARE 28 mm tires. For a brief while I ran 32 mm Paselas on this bike with no issues other than a lack of clearance for fenders and mounts, and difficulty getting the brakes to open wide enough to allow wheel removal. Had I continued to use them I would have replaced the brake levers with quick release-equipped units to augment the caliper-mounted q/r. The 32s certainly FELT nice, and I may yet figure out a way to get them to work on that bike.

I also have a set of Mavic Module E 27-in rims, which are also 13.something wide internally. I have been running Pasela 1 1/4, i.e. 630/32 with no issues and a very cushy ride indeed.

Super useful insights there, Rusty.
The frame clearances will be interesting, esp as the wheels are 27inch, not 700c. It's showing 45mm down at the bottom bracket end which should be enough...I HOPE!

With rims of this standard width, the tire's bead becomes the issue, IMO. Small or large diameter, if the bead is too thick, like, say on a Schwable Super Ultra Marathon Anti-Flat 8000 Touring RhinoForceLiner XX-Tra Tuff5X, then the tube's valve stem can't be wedged in between. Folding bead tires tend to be a lot better about this, regardless of tire diameter/size. I run 700C Mavic MA2 rims (same profile as MA40s) with "33mm" Soma Supple Vitesse EX tires with zero issue. The 33s measure closer to 30mm in width. I've also mounted those same Somas in 38mm size (36.x actual width) on those same MA2s and they were totally fine.

The whole "2x the inner rim width = max allowable tire width" is a nice starting point, but there are other variables in play, and as other tire threads have seen, old MTB tires were mounted on narrow rims like these, and it wasn't the end of the world. As long as your bike has the brake bridge, fork crown, and chain stay clearance, 32s won't be a problem. And if the bike came with 27" wheels originally, it should clear even easier.

In the late 1980s, skinny rims on MTBs were popular for a while. Keith Bontrager took 36h MA2s and MA40s, cut them down to the proper length with 32h and re-rolled them for 26inch MTB tires. I rode a pair of those Bontrager MA2s for years with the normal 1.95 inch tire of the day. I never had a problem.

I've got 32 mm Folding Paselas on 27" MA40 rims. I think they were made for each other.