Like pcrump said, if the backspacing is similar and you aren't having rubbing issues now you should be OK.
For a long time I had 33X12.50 tires on a 15 X 10 wheel with 3.625" backspacing; I had slight rubbing on my front bumper at certain turning angles (remedied by slightly trimming bumper).
Last year, when I went to 285/70R17 tires and 17" wheels I couldn't find anything with a backspacing less than 4.5". I started having rubbing on my radius arms when turning fully.
You may not have that problem since you are going with a slightly smaller diameter tire.
Good luck!