Rear tyre specs and dilemma for IS250

[Hugh R]

I'm thinking of buying a 2006 IS 250L and the owner has said he will be replacing the two rear tyres which have low treads. These are 18" Spider design wheels. All Kumho.  The fronts have good treads:   225/40 ZR18 92Y.  The rears which will be replaced are:  255/35 ZR18 94Y.  I'm slightly concerned as the rears are not the specs suggested by Lexus: 255/40 R18 95Y.  The wheels and tyres were supplied (I imagine new) from a main Lexus dealer.  He says that's how they came, so he thinks they must be correct.  So the question is, should I ask for replacements to be 255/40 or would it be safe to leave well alone when he might replace like for like, i.e. 255/35.  I'm no expert and he says he isn't either.  Advice needed please. 

[royoftherovers]

If the sizes don`t accord with the Handbook or subsequent official Lexus information stated in writing, then your Insurers will need to be informed and they may or may not agree to insure you.

If you are not completely comfortable, then my advise is do not buy it Hugh. Good luck.

[scudney]

If you are otherwise keen on the car and everything is spot on regarding your needs/requirements i would suggest you ask for the replacements to be 255.40.18's(I have heard of people running on 255.35.18's)however I have always liked sticking to recommended sizes personally, admittedly there is a variation of sizes.👍👍