any reason why you'd want to put 215's on? they'll be taller as well as wider as the 40 part of the profile is a percertage of the width of the tyre
 
davidol said:
any reason why you'd want to put 215's on? they'll be taller as well as wider as the 40 part of the profile is a percertage of the width of the tyre

I was aware of that, which is why I asked if they'd fit, I just thought as I've got to buy 4 new tyres soon are 215's gonna be worth it ?
 
They do fit. I was sent 215/40/17's by mistake by mytyres and because my rears were so badly shagged i couldn't be bothered with the hassle of sending em back, so i banged them on anyway. They do rub badly with 15mm spacers on but are fine as standard. Because they are on the back it doesn't about speedo reading but on the front it will make it more inaccurate.