upgrading to 15" rims does nothing for stability and handling in and off
itself

it is the quality and size of the tires that impact stability and handling
same goes for whether you can go off road in the van which you say is a
major goal

depending on tire choice you can get a bit more ground clearance with
tires for the 15" rim and you have more tires to choose from in 15"  but
you must get the right tire

the BFG AT KO in the 14" size has been used successfully by many people,
even folks with Syncro's who go off road very often, very good on and
off road

but if you use tires other than low profile tires, which you don't want
for off road, you will loose some power with the larger diameter tires
that you would put on the van for off road use

you don't say you have a Syncro, so I am assuming 2 WD and only moderate
off road conditions

unless the added ground clearance is an issue, I stay with the wheels
you have and use the BFG's

search this tire's name in the archives of this list and the
syncro@yahoogroups.com list to see how folks feel about it

--
Sam Walters
Baltimore, MD

89 Syncro GL
85 Westy Weekender
84 Vanagon, original owner, soon to be retired, just too many problems

All incoming and outgoing email scanned by
automatically updated copy of Norton AntiVirus.