which bike tyre for my wheel?

[encephalopathy]

i have a boardman hybrid comp but find the tyres on it are not giving me enough grip when not on tarmac now the weather is changing...

Rims: 700c Alex double wall black 32 hole disc rim with CNC braking surface
Tyre size: 28c
Tyres: Vittoria Zaffiro 700x28c rigid black

any suggestions on a grippier tyre/size i could change to for the winter?
will 700x30c tyres fit on those rims ok?

thanks for any suggestions

 

[encephalopathy]

well quick update
bought a pair of schwalbe cx 700x30 cyclocross tyres from chainreaction. they have a little tread in the centre and knobbly bits at the sides. first impressions are the bike ride is less crashy, grip is much better when not on tarmac but flipside is i am going a little slower than before. they cost 13 quid each.

i plan to use them over the winter and swap back to the slicker tyres when the weather improves in the spring.