Tire/Rim Sizes on 80/90/Q's (Help)

[The Judge <dismiss@earthlink.net>]

Gents:

I have been told that the biggest tire and rim combination I can put on 
my '90 80Q are 16 inch rims with 225/40ZR-16.  I have Pirelli P700's on 
now that are 195/60HR-14's on the stock rims (BBS mesh lookalikes).

I want to put Borbets on at 16 inches, and the tires I want on 'em are 
the Dunlop SP Sport 8000 at a low profile.  Dunlop says this combo will 
work, but they are almost an inch wider and the clearance (lateral and 
vertical) will be less also.

Has anyone put anything less than "50's" on their wheels (i.e. 
225/50ZR-16)?  I know 40 is a pretty low profile, so will there be major 
BuMpS to be felt with these?  Should I put 45's on and will they fit?

Thanks,
Todd

The Judge
90 80Q (Terror of Los Angeles)
86 VW  Scirocco 16V Wolfsburg
85 5KCS  (not missed at all)