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.