Do a search on
www.tirerack.com for snows for 17" rims. I don't think there is much there. The Pirelli all season tires in 225/55-17 are rated better for snow than the Synchrones and are cheaper.
If you want to go to 16" rims then a lot of options open up. Most of the Freelander owners who drive in the Sierras swear by BFG TA/KOs which are also good off-road tires. You can get them in 225/70-16 and use them successfully on the Freelander without a lift. They also give you about 1/2" of lift over the Synchrones. The next size up is 225/75-16 but without a lift you will get some rubbing. Also they are 29" tires so the loss of torque to the ground is about 8% - probably more than you want.
Hope this helps.
