Hi All,

I was recently in the market for a set of Schwalbe tires and scoured the whole internet. I actually already have 3 sets, Marathon XR, Big Apples and a Marathon Winter tires. In looking around for a set of Duremes for a new bike, I couldn't find a lot if reliable size info. I remembered Wallingford Bike Parts had a blog entry https://wallbike.com/blog/2008/08/17/...nflated-sizes/

Where they ask people with Schwalbes to list the actual mounted size. It would be a great resource if there was more info listed, particularly since some of the tires prices are now jaw dropping high. So could you Schwalbe owners head over there and list some of your sizes? (I have no connection with WBP except having bought a saddle from them 2 years ago). I just think it would be great for people to have a resource before shelling out $100-$200 for a set of tires that might not fit.

Thanks.

ETRO number is about rim/ bead interface, 2nd number on the tire spec is width.

I agree that it's nice to know if a particular tire runs big or small before trying it on your frame. Have you contacted Wall Bike to see if they have an updated list?

If nothing else, you could buy a set and take some measurements for science.

Thanks, It's not about the tires I am looking for now (actually just bought), but a public service type of thing. I know Schwalbes are popular, I also know the advertised width and true width can be several mm's apart, such as 4+ which is a big difference. Thought it would be good to have a central location for the info. Might even work well as a sticky on the touring forum here....

The actual width on the bike will vary with the width of the rim. A narrower rim will cause the tire width to get a bit narrower too.

I think it's the "inner well width" that really makes the difference. It seems like the outer width of the rim is more often published. Maybe there is a quite standard difference between these?

Anyway, if folks are reporting actual tire widths, it would be helpful to have some rim info along with it.

I have Schwalbe Marathon Winter tires on now, 26x1.75, on Rigida Andra 30 rims with 19 mm inner well width. I measured the width as 1.75.

Tricky to get really precise with such a measurement! I improvised some crude calipers: I have a carpenter's square, and then I took a magazine and kept one edge flush with an other edge of the square. The spine of the magazine was thus parallel to the other edges of the square, with a gap between the magazine spine and an inner edge of the square. I could slide the magazine, keeping its bottom edge flush with the bottom outer edge of the square, until it was snug against the tire, the inner edge of the square snug against the other side of the tire.

Here's my attempt to estimate mathematically how tire width varies with rim width...



T is the distance along the tire from bead to bead. r is the radius of the circular shape the tire cross-section assumes when the tire gets inflated on a rim of width w - width being the internal well width where the tire bead fits. The width of the tire is then 2r.

Here I plot r versus w for several different tires:

This plot should be more legible:

Why do you need to know?

The listed tire width won't be precise, but it will be close. If the tires you have now have little frame clearance, I wouldn't buy anything wider.