Is there a reference/source/method for definitively determining the width of a bicycle tire without actually having it in hand?

I ride a 2009 Jamis Aurora which came stock with 32 mm Vittoria Randonneurs. I wore the rear tire through, so I did some research on new tires and the 35 mm Schwalbe Marathon Mondial sounded like it fit my needs. Googling around forums, I gathered that it would be fine to put a 35 mm tire on the Aurora. This turned out to be not true -- it seized up against the frame right away. Interestingly, the contact was actually on the chain stay, not the seat stay.

I'm a little bummed out by that, but I put the Mondial on the front (which fit fine) and threw the (formerly front tire) Vittoria Randonneur on the rear. Having now riden on the the Mondial, it makes huge difference: it feels way nicer than the Randonneurs. I want to know what I can replace my remaining Randonneur with, but am concerned about it seizing up?

For the record my rim width is 20 mm.

On a side note, doesn't it seems odd that a 'Touring' frame cannot support a 35mm tire?

  • 2
    If the contact was on the chainstay, it should have been contacting both chainstays evenly, unless your wheel was warped, or not seated properly. Are you sure this wasn't the case? On a touring bike that can accomodate fenders, it seems odd that 3 mm (1.5 mm radially) would cause such a problem.
    – Kibbee
    Oct 15, 2013 at 14:12
  • @Kibbee yep it was definitely in contact with both chainstays. I should've taken a picture... there's was no mistaking that these tires weren't going to fit. I think the issue is that the 35mm Mondials are more than 3 mm wider than the vittoria randonneurs (Despite what there stated 'size' is). Incidentally, I do have fenders on, but that's not the issue -- they don't contact the fenders.
    – Joe
    Oct 15, 2013 at 14:19
  • It does seem odd, considering the tire rubs against the stays without fenders even installed. Not all touring bikes are created equal, sadly.
    – WTHarper
    Oct 15, 2013 at 14:26
  • Question: How much are you willing to spend on a tire? What kind of riding do you do?
    – WTHarper
    Oct 15, 2013 at 15:10
  • Yeah, odd for a "touring" bike to not handle 35s. But the rim width has a little to do with it -- my bike fits 35s nicely but the rims are much narrower. Oct 15, 2013 at 16:05

2 Answers 2


I have had similar issues with mountain bike tires. While the industry seems to have done a good job of standardizing rim sizes, tire width seems to vary. One brands 2.0 inch tire can be larger than another brands 2.1. Of course there is some variances with rim widths and tire pressure and tread design, but overall it seems there are no meaningful standards for width. This is where a good relationship with your local shop can be helpful. They may allow you to try sizes and brands to find a good fit. The added cost of buying locally may be offset by not paying return shipping.


The actual width of a mounted tire will depend on the width of the rim it is mounted on.

Different manufactures presumably use a 'nominal' rim width for each tire width, which they do not quote, so the stated tire width is at best a guide.

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