Which ones to go for?

[AlexHealy]

Currently on my car are two each of the following:

225 40 ZR 18
255 35 ZR 18

I have found a couple of sets of tyres with the following, which would be the easiest to replace?

235 55 18
245 35 18

Alternatively I can get the mixed set:

245 35 18
245 40 18

 

[clancy]

easiest to replace? tyres a tyre, same effort to replace any

 

[AlexHealy]

Easiest was probably the wrong term, which would be most suitable?

 

[mat-nos]

most suitable would be the size you have on now!!!
the rolling radius on the mixed sets you listed are not the same.....

 

[skydiver]

http://www.1010tires.com/tiresizecalculator.asp