Looking to get new tires for my ~87' Peugeot Orient Express. Hoping for a gravel but there's a lot more options in 26" going with MTB tires. Aside from measuring the width of the fork and chain/seat stays where the tire sits, are there are any other considerations for how big a tire I can use? Hoping to go with something pretty chunky in the 2"+ range - any issues with bigger tires and the old stock aluminum rims?
Thanks!

[QUOTE=partyanimal;22283635]Looking to get new tires for my ~87' Peugeot Orient Express. Hoping for a gravel but there's a lot more options in 26" going with MTB tires. Aside from measuring the width of the fork and chain/seat stays where the tire sits, are there are any other considerations for how big a tire I can use? Hoping to go with something pretty chunky in the 2"+ range - any issues with bigger tires and the old stock aluminum rims?
Thanks![/QUOT
Back in the day (like similar to the era of that bike) it was pretty standard practice to run 2" tires on really pretty shockingly narrow rims (17mm ish). It'll probably be fine, perhaps stay away from especially wide tires (2.4"+).

As you increase tire size, tires grow in diameter about as much as they do in width. So check the tread clearance to the fork crown, seat tube and brake calipers or any other part of the frame the tread is close too.

Old stock rim probably won't be an issue with any size tire you can fit on that bike.

Another detail is if you're running cantis or linear pull brakes with a narrow rim/wide tire combo. Often the top edge of the brake pad can graze the tire's sidewall just above the rim. So do check for that or the pads will machine through the side wall like a lathe tool goes through metal. Andy

The stock rims are described in the catalog as 26"x1.75"* so I'd imagine they're plenty wide for the tires you want to use. If you have tires on there now, you can use allen wrenches as feeler gauges to estimate how much bigger of a tire you could fit in there. That works best with slick tires, but if you find that you just won't be able to fit anything over a real 2", that could save you the aggravation of having to return 2"+ tires that don't fit...

* Stamping the recommended tire size into a rim isn't my favorite practice but they started doing it before I could say anything about it.

I'm still pissed about Centigrade to Celsius. We didn't get to vote!
Something that made sense to something that sounds like a-
distant planet
radioactive element
one of several different diseases

Do any do that? I'm just happy when I see the ISO size of the rim printed on it whether it's stamped into the rim material or on a printed label.

I'd have thought tire makers would be the ones to suggest what size rims a particular size of their tires should be put on and not the rim makers suggesting what size tires.

That's what I've always assumed when I see "26 x 1.75" or "27 x 1 1/4" stamped into a rim, since 1.75" or 1 1/4" didn't otherwise correspond to any part of the rim itself. To pick on one brand, Ukai would stamp rims with very specific tire-sounding sizes: https://velobase.com/ListComponents....6-886f460f73e2

Of course, that was for rims from the 70's/80's, seems like they're generally hip to ISO/ETRTO these days.

Now that you wrote it like that I guess I have seen that quite often on some rims and just never thought about it. I tend to just ignore any sizes I see that aren't ISO/ETRTO sizes.

I got burnt by this on a Japanese sport touring bike. Had to file down the bottom of the head tube to fit a frickin 25mm tire.