UKC

Rims 17-622 so tyre width up to 50mm?

Current tyre 700x38c, also marked 40-622 and 28x1.5.

https://www.schwalbe.com/en/mtb-reader/smart-sam-plus 

Will 47-622 tyre work? 

700x38 to 28x1.75 is 11mm greater diameter and 9mm wider?

Actually 1.75inches is only 44mm not 47 so I'm confused what 47 of 47-622 is!

So if current tyre has more* than 5mm clearance all round 47-622 will fit frame as well as 17-622 rim.

*significantly more, still need 5mm??? clearance with bigger tyres

What a mix of units and standards!

I only understand 700x road tyres.

Is this on a gravel bike? If so clearance is as likely to be the issue as rim width. I put a 50 mm new front tyre on my gravel bike but only a 40 mm at the back and I don't think there is clearance there for much more. Not sure what width my rims are but they had always had 38s on them before, but take 50 mm with no issues.

Thanks!

I think "adventure" bike was the marketing term that year, so gravel like clearances (thumb width at forks, finger width on rear stays, not done proper measurements yet!).

So 622 is the factor for rim compatibly?

https://www.sheldonbrown.com/tire-sizing.html

622 is the ISO standard number that relates to rim diameter (it is the diameter of the bead seat, not the overall diameter) and is equivalent to 700c which originated as a French standard.  17 is the distance between the rim flanges, if you get a tyre designed for a significantly wider or narrower rim it could well cause problems.  The link above explains it far better than I could and has pictures and tables, one of which suggests the safe range for a 17mm rim is 25-37mm tyre width.

https://alexrims.com/faq/ suggests 25-50 for 17c (not sure what that c means).

Bit of a scary discrepancy!

C denotes a crotchet rim, which is one with an internal flange to engage the bead of the tyre as opposed to a straight sided rim, which somewhat fell out of use in the cycling sphere but has made a reappearance fairly recently with tubeless tyre/rim combinations without hooks.

So if it catches the bead that might account for the larger max tyre size.

Rims are Alexrims C X D 26.

All very confusing!

Tried fitting schwalbe sam smart 47's to my escapade and what I failed to take account of was side knob protrusion. They hit the chainstay but not the seat stays. The other dimension to careful of is to the back of the seat tube...

Many thanks. The above comment was spot on - 6mm clearance to chain stays, other narrow spots were 10mm to front mech clamp on seat tube and 12mm at crown of forks. Measured by prodding in screwdriver and tools with various diameter shafts to see what would fit and not fit in the clearance.

That's 6mm clearance with tyre marked 700x38c, 40-622 and 28x1.5.

Anybody know if sizing includes knobbles?

Assuming sizing does not include knobbles I think I can do same size tyre with knobbles.

42-622 (28 x 1.60, 700x40C) version of smart sam plus, only marginally bigger than 700x38c.

https://www.schwalbe.com/en/mtb-reader/smart-sam-plus

I guess if I just buy one and it doesn't fit on the back it will be OK on the front and I can look at something else for the back.

Thanks everyone!

I think the biggest issue with saying yay or nay is that it depends on what size rim they are going on as that will affect the width of the casing when inflated. I specifically had problems on the chain side of the bike and I ended up hacking off the side lugs with a grinder which was sub optimal...

622-17 rim, same as current tyre so in theory similar effect on width.

Angle grinder on rubber - that does not sound like a pleasant job!

Don’t forget .. same rim, same size but a different make and/or model of tyres can have different widths in practical use due to differences in flexibility of side wall/carcass as well as differences due to pressure differences; wider tyres are usually run at lower pressures also which don’t help.

I’ve changed supposedly identically sized tyres on same rims, but from a different brand and found a notable different overall width such that my chain was rubbing on the side wall on the largest cog when in use. Partly it was a softer side wall allowing flexing and spread more and partly the width turned out a bit wider anyway*. Had to run them at much higher pressure to minimise this. Plenty of clearance on frame, etc., only noticeable whilst in use.

BTW, I used last winter Smart Sams at 2.25 wide on another bike that has 2.0 tyres currently for summer. Was plenty of clearance and side knobs didn’t seem to add extra to width in any notable way on that bike.

Edit: * Ha ha I see in the tyre sizing link above the para dishonesty in sizing!!

Thanks everyone, the new tyres arrived and I fitted them this evening.

The Schwalbe Smart Sam Plus 42-622 (28 x 1.60, 700x40C) don't rub on frame or chain.

There was 6mm clearance form chain stay with tyre Schwalbe Marathon Plus marked 700x38c, 40-622 and 28x1.5.

That chainstay clearance reduced to about 3mm, hopefully that will be enough as it'd probably what it was when I had full length mudguards with the old tyres.

Thankfully I've never had a puncture with Schwalbe tyres, I don't think I'm strong enough to get them off & on at the roadside in the cold & wet!