Hello,

On my Hybrid Giant Fcr3, I mounted 42-622 (700c - 40 ) Schwalbe Plus tour.
Everything is ok except under the fork
With that tire, i got only 2mm space between the top of the tire and the fork..
That seems way too narrow if anything happen to my tire...
So I'm ok to get less fat tire, but how do I know the height of it before buying it ? It is not written anywhere...

I could go for 40-622 , 37-622, but do their height is different ?

Thanks

Georges

This is where the LBS is a value. One can ask them to mount the tire on your rim (not a different one) and either test fit or measure directly. Or you could do the mounting yourself before buying the tire. This is why having a good relationship with the LBS is a good thing. Hope you have such a shop nearby. Andy.

Yeah thats the thing I do not have any close by... But seems that I will still need to travel to it if I want to be sure ! I would have prefered to buy second hand but gonna be complicated.

Put a 35 or 32 on the front.

Yes. Actually Schwalbe gives the approximate circumference for their tires:
Tire Dimensions | Schwalbe North America

So If I divide it by π (pi) I have the diameter, so the height of the tire...

I'd say 2mm is OK as long as you don't plan on mounting fenders/mudguards. I've never seen problems with objects getting caught between the fork and tire and causing wheel stoppage. If using fenders with only 2mm clearance between them and the tire that's a different story and you would definitely be in danger of something getting caught between them. Actually a fork this close might help knock off some debris that could cause a flat.

Ah ok... I thought 2mm was too short for clearance in case my wheel is not true anymore or i got mud in there.. The bike is for touring the carretera austral in Pentagonia (Chile and Argentina)

I say 2mm not nearly enough clearance. Nobody picks up rocks or twigs? I do.
Put smaller tire on.

Ah well, if you know you're going to get some thick, gooey mud then 2mm might cause problems. The more clearance the better for mud. In your case though you're not going to substantially increase the clearance by going with a smaller tire and the skinnier the tire the more difficult it will be to ride through heavy mud. A slight dilemma. Your call.

Agreed with those who say 2mm is too little clearance. I see paint worn off and chipped frequently on close clearance frames, the crown's underside is a common spot for this. I have seen the results of accidents from something getting jammed in the tire/crown gap. Not common but it only takes one time to make your day a bad one.