Widest tyre width on a road bike

[damian]

I know this is pretty much based on the clearance but how comfortably close can the tyre be to the forks or rear triangle.

A couple of years ago I bought a lovely ladies 2006 Specialized Ruby Comp but she's had neck troubles since which makes riding difficult. I've just converted her drops to a straight bar and the STIs to Shimano R770 10-speed shifters to make life easier for her. Now to add a little more practicality to the bike ie. ability to ride on greenways and gravel trails I'm looking at increasing the width and type of tyre.

Any suggestions?

 

[Iwasgoodonce]

Touring or cyclocross tyres could be the job. Tourers go up to around a 38?

 

[damian]

Touring or cyclocross tyres could be the job. Tourers go up to around a 38?

That might be a little too wide

Can I make the assumption that a couple of mm clearance is sufficient or can I go a little closer ie. 1mm

 

[perry]

you can go close to the bridge unless possible loss of paint from stones stuck to the tyre getting wedged through is a concern .it would also be a bit noisy . grab the chainstay with your hand and using the ends of a couple of spokes at the rim end pull the wheel to the stay . thats the clearance you need . when the wheel flexs it very quickly rubs away the paint and ive even seen alloy frames with groves where a knobblie tyre had worn into it