What are the biggest tyres I can fit on an old style touring bike?

[billiobob]

What are the biggest tyres I can fit on my old style steel tourer? I have Schwalbe Marathon 700 x 25c on but find these inadequate on local potholed roads and a bit skittery on paths. Using the tape measure there seems to be at least 10mm clearance on each side for a 700 x 35c tyre such as the Schwalbe Landcruiser but would these be deeper as well? Also would they be robust enough?

 

[MichaelW2]

My Bob Jackson tops out at 32mm + "guards. It can take a little wider without mudguards.

 

[Vantage]

How much room do you have around your current tyres? Any chance of a pic?
I've never hated myself enough to use Marathons but from what I've read from other users, they aren't the grippiest of tyres.
Any 32-35c road tyre should be good enough for UK roads and some light trail use. Scwalbe's Roadcruiser is a good cheap tyre.

 

[Cycleops]

As Michael says 32 would probably be max. I think others have said that's the same for a Galaxy.
They will be deeper too although that shouldn't be a problem with the longer wheelbase on a tourer. You need to check clearance at the top of the fork too.
Only real way of course is suck it and see.

 

[bonzobanana]

Different tyre designs mean there so called size can vary a bit. Not all 700x28c tyres are created equal some may fit where as others won't. Also you get a mismatch sometimes with more clearance in the front than rear etc. So you could have a mini-mullet arrangement where you have a slightly bigger tyre on the front compared to the rear. Maybe 700x32 on the front and 700x28 on the rear etc. This might give you a little more grip and comfort at the front although might mean a few tweaks of saddle and handlebar angle.

 

[billiobob]

 

[billiobob]

Urgh! These close ups certainly show up the need for a clean! As requested Vantage, thanks to bonzobanana and Cycleops for your helpful feedback. Just to clarify my cycling is limited to short rides as much off road on paths as possible so that will influence my tread choice.

 

[iandg]

If the frame has horizontal drop outs it allows you to pull the wheel backwards and the gap between chainstays will be slightly larger allowing for a slightly fatter tyre. Can do this with my cross-check.

 

[Cycleops]

I would have thought you should be able to get 32s, maybe even a 35 in. But then there's the mudguard. As @iandg says the drop outs might give a bit more wiggle room.
Shame you don't live down here you could pick up a cheap 'home used' tyre to try.

 

[Jenkins]

Different tyre designs mean there so called size can vary a bit. Not all 700x28c tyres are created equal some may fit where as others won't. Also you get a mismatch sometimes with more clearance in the front than rear etc. So you could have a mini-mullet arrangement where you have a slightly bigger tyre on the front compared to the rear. Maybe 700x32 on the front and 700x28 on the rear etc. This might give you a little more grip and comfort at the front although might mean a few tweaks of saddle and handlebar angle.

Very much this. The pictures below are of two different tyres on the same Campagnolo Zonda wheel. The top is a 25mm Continental GP4000 while the bottom is a 28mm Vittoria Rubino Pro - note that the GP4000 is about 1mm wider and 0.4mm taller despite being sold as 3mm narrower

 

[november4]

yep, my 28mm continental 5000 measure 30mm

 

[Vantage]

View attachment 658138

I think you're out of luck as I can't see a 35mm land cruiser fitting in there.
You might squeeze a 32mm road cruiser in. Maybe.

 

[Peter Salt]

View attachment 658138

Looking at the photos, I wouldn't go bigger than 32mm. Maybe a CX tyre? You have a Schwalbe and are considering another Schwalbe so perhaps something along the lines of X-One Allround?

@Jenkins makes a good point but that's not how you correctly measure with a vernier caliper

 

[Low Gear Guy]

As Michael says 32 would probably be max. I think others have said that's the same for a Galaxy.
They will be deeper too although that shouldn't be a problem with the longer wheelbase on a tourer. You need to check clearance at the top of the fork too.
Only real way of course is suck it and see.

I have previously fitted 35mm tyres on a Galaxy. However not all 35mm tyres are the same width and it is possible that there is variation between Galaxy frames.

 

[GuyBoden]

Take the mudguards off, get some 42mm tyres and go bikepacking with the cool kids.