I own this bike : speed 2012 ridgeback

The tires are worn out and I have decided to buy schwalbe marathon plus (since I often had flat tire due to broken glass on bicycle paths in my town)

The original tires are Continental Contact 700×37c.

Which size of the schwalbe should I choose :

  • 37-622 28x1.40, 700x35C SmartGuard, or
  • 40-622 28x1.50, 700x38C SmartGuard

I found the sizes on the schwalbe Bike Catalogue

  • 2
    Whichever you want, depending on whether you'd prefer narrower tires or wide ones. Jul 6, 2015 at 12:11
  • @Daniel, you are saying that both schwalbe tires (35c and 38c) will correctly adapt on the rim ? Jul 6, 2015 at 12:13
  • 2
    3mm difference is just about impossible to notice. If the rim is "average" width then one could likely go 10mm wider or narrower, with no difficulty other than possibly fender clearance. Jul 6, 2015 at 12:24
  • @DanielRHicks is spot on, but if you're replacing a tyre which has no or (as in your case) a minimal breaker layer and smoothish tread, I'd go for the slightly smaller marathon plus, i.e. the 35. The breaker layer on this tyre is quite thick affecting the shape and making it more likely to foul on mudguards than the "contact" for the same size, which must then be added to the extra 1mm.
    – Chris H
    Jul 6, 2015 at 14:40
  • 1
    The first number in the size - 700 - is the rim size size. The second number - 35 or 38 - is the width of the tire as measured in millimeters. These second numbers are really only guesstimates since actual tire size depends on a variety of factors and every tire company seems to measure them differently. Either should work fine. Increasing by a few mm shouldn't cause interference with fenders. If it does then your fenders were not properly installed in the first place!
    – ChrisL
    Jul 6, 2015 at 22:16

1 Answer 1


Both of those tires are quite close to the tires that you already have. There is a really good chance that they will fit. Because of the extra material in the SmartGuard layer these tires are taller than they are wide, but only by a couple of millimeters. So all you need to be concerned about is to look at the clearance on your bike with your current tires. Do you have decent clearance between the red of the tire and the crown of your fork and the bridges in the rear (or the fenders if you have the fenders installed)? 10-15 mm would be very comfortable, on my old Trek I've got like 5 mm. I don't have enough room to comfortably run fenders with my Marathons, but I'll be OK until the rain returns :-)

If you have enough room at the top, you probably also have room at the sides, but it is worth looking there too. The more generous the clearance the fewer hassles you'll run into with bits of junk on the road (it can get caught between the tire and the frame) or an out of true wheel – like if you break a spoke. From the look of the bike in the photos you should have plenty of room – the lower edges of the fenders appear to be aligned with the full diameter of the tires and the specs say that the bike comes with 37 mm tires.

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