Wow! What kind of tyres are you riding on? Just so I can make sure I never buy them! Unless you have a habit of riding on diesel affected roads, or riding at VERY excessive speed and lean angles, then surely tyres should not have that much of a negative effect?
I dont know they can sometimes or at least its one of those things thats very hard to disprove once youve kind of lost confidence in a tyre make, as its just feel isnt it, part of me thinks there are more factors too it, like I had Vitorria tyres for a while and often felt they were squirrely as hell in the wet, though I know people rate them quite well for wet weather handling. whilst my current Bontrager ones seem ok in the wet when its raining, but dont seem to handle damp winter weather.
but then I kind of analyse in more detail and generally when Im feeling the bike feels loose, its kind of this time of year, not necessarily icy, but still <10C, and the roads have a nasty film of dirt, mud, combined with the salt treatment and generally a degree of moisture whether its raining or not, plus diesel, which doesnt really go away till the temp starts to rise, and so really has it got anything to do with my tyres at all ?
the roads have felt very slippy, and I dont mean when its been icy, this winter to me.