Tires: Tire size /rim size, rim widths, rim size

Question
QUESTION: can 185/65R15 tires fit on 15 incch rims that had 195 tires on them, will that 10 mm make it undoable?

ANSWER: Dear Simon,
Thank you for using AllExperts!
You ask a good question as each tire size has an "approved" range of rim widths that are suitable.  The 185/65R15 may be fitted on the following range of rim widths:
5.0", 5.5", 6.0", 6.5"
As there are MANY 195mm cross section tire sizes, please specify the tire size you have in mind and I'll inform you if it's acceptable.
DT

---------- FOLLOW-UP ----------

QUESTION: the tires i WANT to install are the 185/65R15 (winter), the seller of the rims told me he had 195 on his rims so i just wanted to be sure before buying the rims.  The bolt postion and numbers is correct, i just want to be sure that these 185(winters) will fit on those rims.  I dont have the rim size but he said he had 195 so i thought you could tell me just with that

Answer
Simon,
Since we only know the cross section width, I can only provide some "common" 195mm tire sizes with the "approved" rim widths.  It's a 'guess" as to what the the actual rims are, but should fall somewhere within these:
195/70R14,15, 16: 5.0" 5.5" 6.0" 6.5"
195/65R14,15, 16: 5.5" 6.0" 6.5" 7.0"
195/60R14,15, 16: 5.5" 6.0" 6.5" 7.0"
195/55R15,15, 16: 5.5" 6.0" 6.5" 7.0"
195/50R15,16: 5.5" 6.0" 6.5" 7.0"
I think we can conclude that you should not mount your 185s on a rim width that is 7" wide or less than 5.0".  It is easy to measure...just put a tape measure between the rim flanges.
Hope this helps!
DT