I recently bought a used 2007 Pilot and just have a few questions. 1. The tires are quite bald on the front. I know I need a 235/70/16. I'm wondering if the 215/60/15 will fit? And if so what affect will it have? I own tires that are barely 6 months old at this size and would consider using them if it is safe. 2. Occasionally there is white smoke coming out of the tail pipe after I've driven for a long time or distance....any suggestions on what to check?