Hi all,

I have added a tool that estimates your tire width based on nominal width and internal rim width.

It's under the /estimate tab.

Grtz

Reddit moderators say that cannot allow such sites/apps.

And: Added ranges to the explore page:

Thanks for the suggestion. I'm not much of a redditter, so I created an account and tried to upload a new subject the r/Velo, but it got blocked by the moderators. Any tips on how to get it through?

Thank you for the endorsement.

Currently when clicking the model 'Grand Prix 5000', there are versions 'STR', 'TT TR' and 'All Season TR'. So you can make a distinction between how the GP5000 expands in general, but also how the All Season TR expands more specifically. How would you suggest we change this?

Hello everyone,

As more and more discussions, podcasts and Youtube video's have been revolving around tire width, I decided to create a community driven bicycle tire width measurements database: rubbersideup.cc . A bit like geometry geeks, but then for measured tire widths. So then you can have a good estimation of whether your tire/ internal rim width combination will fall in the 105% rule, or would even clear your frame.

All added home-measurements can be submitted and would be very well appreciated. Also potential improvements can be posted here.

Cheers

Quote from: Pistonbroke on May 25, 2026, 09:58:33 AM
Tried a 35mm gp5k this morning on one of Peter's 26mm wheels.
Had it on the back. Fast and comfortable, really comfortable. Currently 38mm wam.

Cool, I added this info to the https://rubbersideup.cc/ database.

More inspiration from Cervelo. They should have called it the Mira 5.

As you understood by now, I am not as concered about it as you. But I do understand your point of view. And I like big rims and I cannot lie.

Therefore, the best solution would be (and probably will be) rims like the Duke WRX AERO 42. On the 28 internal, a 40mm (like the Michelin Pro 5) tire will probably blow up to a 43 or so, making is perfectly in line with the rim and being within ETRTO standards. Everyone happy! It will just take some time for the bike industry to adjust.

I do know know how it is with the 32mm tire on 32mm into rims, but for my 36 on 32 I will never reach the side wall. Even in an extremely leaned position where my pedal already touches the ground at 45 degrees from the bottom position, we are still comfortably on the thready bit of the tire.

I'm running 36mm tires on 32mm internal rims. At first I was apprehensive about it as well. Then after running it for a couple of months and liking it, I also saw on the Nero show's Dog or fast bike section that someone with a Canyon Aeroad was running 32mm tires on 32mm internal rims which blow up to 36mm (Nero show on March the 4th, at: 1:07:45) and racing them.

I'm sure the ETRTO have some reasons for not allowing this and thus officially one cannot recommend it. However, I am personally fine running it.

Yea definitely could have gone for 35.

When Zipp first launched the 32mm (or so) internal xplr rim, Goodyear made some specific (labeled size 40mm) tires for it that work well in terms of aero. When you look up the measured width of those tires on bicyclerollingresistance, they are 34mm. So they are just labeled 40 because on a 32int rim they blow up to 40.

Quote from: hubba on May 11, 2026, 12:16:19 AM
I remember Zen having a rim with 28mm internal and 37mm external. I wonder if running a rim like that with 32mm tires would be better than 25mm internal rim with 35mm tires.

The 32mm tire should end up about 35.5mm and the rim would be 105% of it.

Could you link those Zen wheels (cannot find them)? They sound very nice for 35mm tires also. Closest to those I found are Nextie AGX rims (29mm int, 40mm ext). They look great, but the maximum depth is 45mm, and I'd be interested in something deeper.

I found a video of the Mira on bilibli: https://www.bilibili.com/video/BV1u9RsBRETV/

Head tube does indeed not look very thin (which is the main point of this fork style I guess).

I have been running a 40mm ext 32mm int hooked rims with a 36mm tires (Challenge Strada Bianchi) for a couple of months now, and I love it.

Tires blow up to 40mm wide, so nice shape with respect to the rim.

I built the bike 6 years a go to be my road and gravel bike (Merlin Malt G2X in a couple of sizes smaller than my size so the stack is not too high with 2 wheelsets). The frame has 40mm tire clearance. But the times have caught up to it (as 40mm isnt really consideres gravel anymore) so now its just a roadbike with wide tires. The great part is that when I see a nice mtb/gravel trail in a forrest, I can just send it. Also, can run lower pressure.