I just bought a 2014 750 Li Xdrive M Sport and the dealer put a fresh set of 245/45/19 RF Good Year Excellence tires on the car front and back. First question: I live in Ohio and after my first drive in the snow, I noticed a little sliding when coming to a stop. Appears from my research this is a summer tire. has anyone had experience with this tire in the snow? If I need to swap them out, any suggestions for the new one? Second question: It appears that the M Sport should have staggered wheels. Is this correct and should the rear tires be 275/40/19 to go with the 245/45/19 on the front?
As for the tires, I haven't, but, generally speaking, if the Tire Rack has it designated as a summer tire, then it's not designed for optimal performance in cold-weather. I'm guessing most of us in Ohio get by with all-seasons, but if you want optimal winter performance, the best way to get that is using snow tires. Rather than the hassle of having tires swapped on rims, I opt for a dedicated set of rims w/ snow tires. But, I swap 'em out myself which is easily done in the garage and I already have everything needed (torque wrench, breaker bar, jack, & then some). If you want all-season run-flats, looks like the only option in your 245/45-19 are the Bridgestone RE960's. (checking Tire Rack anyway - maybe a google search for your size with 'runflat' might show other brands - I've never had any complaints dealing with Tire Rack though) There's only one runflat 245/15-19 snow tire on TR, Pirelli Sottozero. Non-runflats and the options open up more. Personally, I would run the 245's on all four corners for snows if going that route, as running a somewhat narrower snow tire translates to better snow traction, as the tire has less snow to push out of the way, comparatively. I think particularly for sport pkg. bimmers, they come with a staggered wheel/tire setup, but I wouldn't know definitively what came with your car. BMW seems to shy away from square setups for sport & M pkg. cars, which forces the car to tend to understeer more when pushed - electronic nannies aside, the average driver, if the front end starts to slide, realizing they're going too fast (relatively) will lift off the gas and brake; as long as the car is understeering, that transfers weight to the front, which should, in theory, give the front tires additional grip and stop sliding. If your car came with staggered M wheels (which might be shown if you run the last 7 of your VIN at www.bimmer.work; you might also be able to look up which wheels are currently on your car at realoem.com, use the VIN there too), and they're not on the car now, then the question would be.... what happened to 'em. Looking at one set of 19" M wheels off realoem.com, although not sure if the car selection was completely correct, the rear wheels were only an inch wider, I suppose it could be possible a 245 could safely fit a 9.5"-wide wheel vs. 8.5, but I don't know. It's never good to have a tire that doesn't fit a wheel right whether too narrow or too wide. In any case, most of the time, the pertinent wheel information of diameter, width, and offset are stamped on the backside of the wheel someplace and not easily seen without having a wheel off the car. You could try a telescoping inspection mirror (http://www.harborfreight.com/telescoping-mirror-7361.html) and flashlight, look for 19x8.5 or 9.5 (probably) and etXX, which will be the offset in millimeters. If the idea of dedicated snows are appealing and you don't have staggered M wheels on the car now and/or are ambivalent about the current wheels, I'd stick snows on those, and then buy another set of wheels that you like better (don't forget tire pressure monitors) - if you want staggered, then the decision would be whether to keep two of tires you have now and get two more if they come in the wider real size, or if they don't, then taking the hit for another set of tires altogether and finding a way to unload the current ones. As for me, I would run a square setup all around in the summer too, preferably with the wider size on all four corners, if it fits up front, so as to be able to rotate tires and even out the wear - that would neutralize the handling vs. more understeer, so you'd want to be cognizant that the car might more easily oversteer vs. the staggered setup, but all the electronics would still be doing their part - still, there's only so much that can be done to fight the laws of physics if you get in over your head, but prudent constraint and common sense also goes a long way. If something non-runflat is appealing, keep in mind the absolutely-stuck-in-place-from-a-flat factor, vs. at least the potential to keep rolling if a runflat isn't too hopelessly damaged from something happening.