Tyre Vs rim sizing

[dhd.evans1]

I've acquired a singlespeed steed again, this time with rim brakes instead of disc. It was armed with WTB Thick Slick 25mm tyres but I'm not much keen on them.

Working at a bike project has advantages as we have plenty of tyres (mostly recycled) kicking about. Also, this thing has plenty of clearance to go up from 25mm.

I tried a couple of 32mm Gatorskins on but they kept 'bulging' the tyre at the valve. Tubes are still 25mm for info. The rims say "700x14". I've got a 28mm Gatorskin to sit fine on the rear.

First question, why are the tyres bulging? is it related to rim size? Secondly, do I need to get rims with a larger width to fit the larger tyres?

 

[Ming the Merciless]

Yes, 14mm is below min recommended internal rim width for 28mm tyres. Of course it may just be you did not push valve up when fitting tyre.

 

[Paulus]

I would make sure the tube is pushed up into the tyre before inflating, also make sure the tyre is seated correctly.
The rim may be a little small for a 32mm tyre, but with a little care it should fit on.

 

[Elybazza61]

What they ^ said.

 

[wafter]

This website has a decent table of ETRTO rim width / tyre size comparability; which conveniently starts at 15mm rim wide - however suitable tyres shouldn't be much different to those stated for 15mm - which includes 32mm.

A reasonable quick and dirty rule of thumb is that ideally a rim fits a tyre double its internal width, with maybe 30-40% of tyre width waggle room on either side.

 

[Ajax Bay]

I have run Conti GP4000 28s on an irw 14mm. But that would be the limit imho (and iaw Sheldon: max x2.0 multiple). So the 28mm Gators are fine. If you want to run wider tyres than that: yes to wheels with at least a irw 17mm.

I don't agree with this as written: "A reasonable quick and dirty rule of thumb is that ideally a rim fits a tyre double its internal width, with maybe 30-40% of tyre width waggle room on either side." Edit?
The Sheldon guidelines are 1.4-2.0 of irw. As written "either side" this suggests 2.6 would be OK: a 36mm tyre on a 14mm rim! I don't think so. The "waggle room" is only on the narrower side of "double its internal width".

Wrt bulging at the valve, I recommend the OP removes the knurled nut pulling the valve to the bed of the rim. There is no practical need for it (tubed) and removal allows one to push the valve radially 'into' the tyre and push the tyre beads deliberately 'down' to ensure perfect seating and no bulging. The narrower the rim, the greater the need for this tweak.

 

[gcogger]

I've been running 42mm tyres on 19.5mm (internal) rims for some time. It appears to work very well (and I'm putting a lot of weight on the tyres).

 

[wafter]

I don't agree with this as written: "A reasonable quick and dirty rule of thumb is that ideally a rim fits a tyre double its internal width, with maybe 30-40% of tyre width waggle room on either side." Edit?
The Sheldon guidelines are 1.4-2.0 of irw. As written "either side" this suggests 2.6 would be OK: a 36mm tyre on a 14mm rim! I don't think so. The "waggle room" is only on the narrower side of "double its internal width".

While it's not what I'd spec by choice the link in my post suggest a max of a 39mm tyre on a 15mm rim...

 

[Ajax Bay]

the link in my post suggest a max of a 39mm tyre on a 15mm rim

Fairy snuff. Doesn't seem a site with any 'authority' if I may say so.

@gcogger - yes: fine. The max x2 guideline is/was for 'road' wheels with narrowish rims ie max irw 17mm which you could get calipers round. Nowadays many more are wider (like yours with Vbrakes/discs) and the 2x limit is void.
Here's the 'new' ETRTO chart which also takes into account hookless (TSS) rims (max pressure is dependent on irw and tyre width). Mercifully CycleChat has not descended, sfaik, into internecine warfare on whether hookless is unsafe or not.

and here's the 'Continental' version:

 

[mickle]

Eh? I'm running 2.3 inch (58mm) tyres on an Mavic 231, which is about 17/18mm internal with no ill effects.

 

[fossyant]

Got 38c gravel tyres on some older Mavic Aksiums 15mm.

I've got 28c Michelins that come up more 26c on a 15mm Mavic Cosmic - a wider rim and they would come up wider, but Michelin state the size will be between 26-28c depending on rim internal width.