In extremely cold conditions, i.e.20 degrees ferinheight, one would use 5w-30 oil. In areas where temperatures exceed 120 degrees ferinheight, use 20w-50 weight oil. Follow the manufacture recommendations . There should be a label just inside the driver's side doorjamb, with the proper size listed. Almost all tires installed on cars today are sized on the metric system.
Tires can also have speed ratings .
These are represented by a single letter after the aspect ratio. The letter V stands for the speed the tire can withstand. Tires are also graded by traction. You're driving down the road and suddenly you get a flat tire. First, do not panic.