Originally Posted by KLP 92
Should be 235 40 18 on a 8J wheel all round.
You can go for a wider tire at the rear but not really recommended, unless its on a 9J wheel whena 265-35-18 tyre can be used.
As you are using 235 40 18 at the front and the rear is 245 and the same profile you may experience problems with the cruise control malfunctioning due to different speeds being detected by the wheel sensors due to different rolling radius.
Not experienced any issues with cruise, but I've not really used it for any great distance. Pity I didn't check this a few months ago as I just put new tyres on the rear (same size as the old tyres; 245/40). I just presumed the rim sizes were different. However I had the wheels off today and checked the sizes stamped on the back and found out they were the same.