don't wanna sound like an idiot but what happens if the front tires of a grand caravan have 15 inch rims and the back 16s?

You should use the same rim size all the way around on your vehicle. Are you saying that you have 15 inch rims on the front and 16 in the back?

How much snow are you talking about and have you been through snow with this vehicle before?

OK OK.....ANY TIRE THAT IS TALLER OR WIDER WILL GIVE YOU BETTER TRACTION

This is a front wheel drive, 2 wheel drive vehicle, correct?

Kelly, I don't understand, the rear wheels don't spin unless it's an AWD? Is it?

Tire size, see link below http://www.edmunds.com/dodge/caravan/2005/st-100385376/features- specs/

I would follow the manufacturer recommended size and go to a tire shop before fooling around with this. It could dangerously affect the handling of your vehicle and especially in snow or slippery conditions. Who knows, if you get into an accident, the insurance company may not cover your loss with unequal tire size in front and back. It's an insurance risk management issue.

Read this, http://www.tirebuyer.com/education/using-mismatched-or- mixed-sets-of-tires#.VbQ6d3vn_MI

I DONT SEE WHY NOT.. IF YOU HAVE 15 INCH ON THE FRONT AND 16 ON THE BACK...DONT GO NUTS ARE THEY IN DIA....

Also, this discussion is worth reading, http://www.city- data.com/forum/automotive/1818523-do-all-tires-have-match.html

THE VAN YOU HAVE is front wheel drive..i said a taller tire gives you a bigger contact surface or a wide tire gives you more contact surface ..tall and wider even more....