Technical > Wheels, Tyres and Brakes

Actual size of 559-50/26" x 2.0" Dureme and Supreme Tyres

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kwkirby01:
I'm looking to fit larger tyres to Sherpa to get a little more comfort. The frame will take them and my mudguards (50mm Gilles Berthoud) still have a lot of clearance.
I've measured my existing "40mm" Supremes and discovered they are closer to 34mm...
So, how big are 2.0"/50mm Duremes and Supremes when fitted - does anyone know?
Thanks, Kevin

Danneaux:
Kevin, I had the same question when I got my first pair of Duremes, so I measured them with a caliper.

I found the actual width varied as a result of pressure, age (they stretch ever so slightly with use), and the width of the rim they are mounted on.

I have 6 pairs mounted on 3 bikes. The narrowest combination when new was mounted on a Rigida/Ryde Andra 30 rim and was an actual 47.1mm wide. The widest is a well used Dureme (standard, not tandem edition) on an Andra 40 rim on the rear of my tandem. It measures 49.237mm wide.

Best,

Dan.

kwkirby01:
Thanks for the prompt response Dan. Any idea of the height, which I think might be the limiting factor on my bike.

Danneaux:
I'll check when I get the chance, Kevin. Most bicycle tires (not all, but most...depends on the angle of the bias plies) have a 1:1 ratio where height from the edge of the rim to the outside of the tread is equal (or nearly so) to the inflated width at the widest point.

EDIT: If it helps, Thorn fitted Mk 2 Sherpas with 2.0 Duremes as standard back in 2011 and to the end of the production run. I had no clearance issues running 26 x 2.0 Duremes on my 2011 Sherpa Mk 2 with SKS P55 mudguards. Thorn had fitted nuts as spacers between the 'guards and the brake/chainstay bridges and under the fork crown. There would have been even more clearance with those removed. Photos attached to show how things looked.

All the best,

Dan.

Danneaux:
Okay...just checked. To make sure of a maximum measurement, I pumped 50psi into one of my Duremes mounted on an Andra 30. The 1:1 ratio held. On the front of my Nomad Mk2, the tire measured an actual 47mmx47mm (rounding fractional millimeters).

As I mentioned earlier, most but not all bike tires inflate to similar 1:1 profiles (or nearly so). In the early--mid 1980s, Panasonic introduced and marketed a tire for the triathlon market that had the belts biased so the tire constrained laterally and allowed to grow vertically so it was oval when inflated. In those days, even racing bikes still had pretty generous bridge/fork clearances but often had narrow forks. The idea was to add some cushioning and rim protection vertically while keeping the tire as narrow as possible. It sold very poorly and was discontinued shortly thereafter.

A touring bicycle I purchased in 1989 was equipped from the factory with radial tires, a special model supplied to the maker under contract and again from Panasonic. I soon swapped them out for standard bias-ply tires because while they worked well enough, they felt horrible under me. The tread would stay planted while the sidewalls would move sideways over the contact patch, making it feel as if the tire was sliding out form under me, especially when cornering and carrying a touring load. The only "cure" was to run them inflated so they were rock hard, which defeated the purpose. They were soon pulled from the market as well.

'Hope the measurements help you.

Best,

Dan.

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