affects of tyre width on speed

[tbtb]

If the OP is thinking of new tyres for speed, first thing to check is that he has the first essential: a (floor, ideally) pump with a good big pressure guage on it. £15 well spent, lets you put current tyres at their exact max and at various other pressures, to find what works best for you. Different terrain, different rider, different best tyre.

Grab a set of 23s cheap, sure. Might be wise to google your rim first, have a look at the manufacturer's webpage. Not guaranteed that the rim will be happy with a 23.

 

[Banjo]

I think the tyre weight has more effect than the size. I use very heavy Michelin City Pilots 32c on my commuter bike in Winter as they are incredibly tough. When I change to the same size but much lighter Bontrager racelight 32c summer tires it feels like a new bike much faster and more responsive.

As soon as its daylight on my commute both ways I change to the bontragers and its a relief.

 

[Chris S]

I'd have thought tyre pressure would have had more effect on speed - mine were way under and I've just pumped them up. The bike is noticeably faster.

 

[tbtb]

I'd have thought tyre pressure would have had more effect on speed

Narrow tyres have higher max pressures.

 

[rualexander]

Another thing that affects this subject is the road surface, if it is very smooth tarmac then narrower tyres will be best as they are lighter weight, but if the road surface is the harsh 'knobbly' kind of tarmac then wider tyres will roll better.
In both cases you want to have tyres with supple sidewalls to minimise rolling resistance.
In my view, lighter weight to reduce rotating mass and supple sidewalls to cope with the 'knobblyness' of the surface will make the most difference rather than purely looking at tyre cross section.

 

[RecordAceFromNew]

Narrow tyres have higher max pressures.

+1 and actually narrower tyres should be run at higher pressure. As can be deduced from the respective shapes of the contact areas - else one will get pinch flats and/or rim damage more easily than with wider tyres. The relationship is essentially inverse proportional - e.g. halving the width needs doubling the pressure.

 

[HLaB]

Narrow tyres have higher max pressures.

Whilst I'd agree with you there are some minor exceptions my 25mm Vitoria Rubinos are rated to a max of 130psi where as my 23mm conti Gran Prix is only rated to 120psi max (not that it makes much noticeable difference at that level)