[QUOTE=DinanX5]Actually, 295/40 20s won't make a significant difference in overall diameter (741.7mm) from most OEM combos (my 255/55 18s are 734.1mm; OEM 255/50 19s and 285/45 19s are 739.1mm) if you used them in the front and the back, but they do require at least a 10" wheel, which I'm told will cause rubbing in front, so they're not recommended for front use. And if you tried to combine them with the 275/40 20's - which are a little smaller in diameter than other stock combos (729.0mm), than you would have somewhat of a mismatch...
QUOTE]
Maybe I wasnt clear!
Humble X5 asked if 275/40 with 295/40/20 would be ok?I correctly advised that his rear end would be 16mm raised!
He is also asking for our advise on 20" tyres ONLY as this is what he is going to install.I believe I am also correct in saying that 295/40/20 is again up 16mm on 275/40 and 315/35/20..Hence I recommended he go for the latter.
With respect to the oem measurements,I agree with you(give or take a few mm!)and 295/40/20 only makes a 7-10mm difference up on oem set ups.
I have a formula to work out the correct figures which give me:-(rounded off)
235/65/17...737
275/40/20...728
315/35/20...728
295/40/20...744
255/55/18...734