Change Of Tyre Size

[Dizzy90]

Hello ford lovers !!

i urgently need 2 new tyres on my car , they are currently 235/45/17 on my ford mondeo . i have being to my local garage where my mate works and he has some 245/45/17's in , would it be ok to swap the 2 front ones to 245 ? .. would this make the driving worse or better or the same ?

[BOF]

Difficult question: on the same pan dimension (assuming these tyres are allowed for that pan), the 245s may allow a bit more steering 'lost motion' (that's not a strictly accurate term, but it is an amount of steering lock that does less work for the same change of steering wheel angle, than it would at higher steering wheel angles), but more grip. Now that would be fine, except that different brands and series of tyres will have a different amount of steering lost motion, so the end result is a solid 'who knows', or thereabouts.

It shouldn't trigger excessively early trac control, which the other way around it could, but there might be more susceptible to early ABS activation; I really doubt that this is a noticeable problem with this relatively moderate size change, but I don't know.

There is the possibility of some tramlining, but again some tramlining is probably inevitable in this kind of size and its probably not much worse in 245s, so I'd guess that most people would find this tolerable, but, if you are particularly sensitive to tramlining then maybe you won't be one of them.

They will also throw the speedo out a bit - only 1.38% theoretically, and your speedo is probably over-reading by that anyway, so that part is unlikely to be a biggie, in practice, although if you have been used to the speedo giving you a safety margin for speed cameras and the like (who me, officer?), that may now have gone.

[Dizzy90]

Thanks for that , if i swap the front ill more that likely end up doing th back 2 aswell . if the tryes are wider , help me from curbing alloys , as just had them refurbed and sprayed .