mogse said:
I'm looking to change my tyres on my road bike to some with some grip for use in the wet, i currently use 700x23 continental gp4000 which are slicks.
i have looked at some winter tyres with some tred which i think they class as city tyres on the follwing site. but the only sizes they seem to do are 700x32c will these fit my road bike wheels or do i need to get new wheels?
Many ROAD bikes have a problem fitting 700x28 tyres, now; so, it is definitely problematic whether your bike will even handle 700x32 tyres.
An arbitrary rule-of-thumb would be this -- if your frame does not have fender eyelets near the dropouts & if it was made in the last half-dozen years, you may be hard pressed to fit 700x28 tyres ... if your frame & fork have fender eyelets, then you can probably fit 700x32 tyres.
Now, whether or not you need new rims is probably a matter of some dispute. I know someone who chose to put 700x32 tyres on his MAVIC MA40 rims (622-15) ...
CX racers generally use wheels with 622-15 rims ... sometimes, 622-13 (e.g., MAVIC Ksyrium SSC SL/SL2/etc. clinchers which have tubular "sister" options) are used with CX tyres.
If your bike frame can handle 700x32 tyres, the biggest problem you may find will be fitting the tyre past the brake caliper when installing/removing the wheel -- this may-or-may-not be a nuisance where you would install the wheel with the tyre only partially inflated and then inflate the tyre to riding pressure after the wheel is mounted in the frame.
If it is a nuisance, then getting/using wider rims (e.g, 622-17 or 622-19, with the actual brake surface being about 5.5mm more than the "bead" dimension) will result in having the brake pads set wider which will make fitting the wheel easier ... of course, that will mean that you'll need to adjust the pads, again, each time you switch back to your normal tyres and/or wheels.
Don't forget to buy different (i.e., larger) tubes for the
fatter tyres.