Replacing hub caps on your vehicle may sound like a simple procedure, but that will be determined by the make and model. If you're replacing original equipment hub caps with aftermarket hub caps, remember that you get what you pay for. The more inexpensive the hub cap replacement, the less likely it will endure. Replacing hub caps with original equipment, on the other hand, can be extremely expensive. Determining what your budget is and what you're looking for to cosmetically cover the wheels of your car will dictate how simple the hubcaps are to install, how fancy they look, and how costly they will be.
Look on the sidewall of the tire to determine the tire size. You might also find the tire size on a label located in the driver's side door jam. The last number of your tire size is the diameter of the tire and will tell you what size hub cap to be looking for to replace on the vehicle. For example a 195/75/15 tire size would indicate the diameter of the tire is 15 inches so a 15-inch hub cap replacement is what you'd be looking for.
Determine what kind of hub cap you want to replace on the vehicle. If you've damaged or lost an original equipment hub cap, chances are you're going to have to obtain one from the dealership, a local junkyard, or perhaps on an online shopping service such as eBay.
Determine how the hub caps are affixed to the wheels by inspecting the remaining ones. There are several different types with several different options. Look at the hub cap carefully to inspect what is securing the hub cap to the wheel before trying to remove. Trying to remove a plastic hub cap before it is unlocked, unhinged, or unscrewed will damage the hub cap. Many GM models have lug nut caps that screw onto the lug nuts and hold the hub cap secure to the tire. These can be removed using a ratchet and socket or a lug wrench end. Some models have hub caps that simply pry off with the flat end of a lug wrench end or a pry bar. Some fancier cars with spoked hub caps may very well have locking devices on the hub cap that lock the hub cap to the wheel and require a key to remove.
Before purchasing a new hub cap, always find out if you can try it on the vehicle first. Many places will allow you to do so or will even assist you. Before purchasing online, find out what the return policy or procedure is. Make sure you can return them if they do not fit for some reason.
Line the valve stem up with the allocated spot on the hub cap for reinstallation. The same would apply with the screw on lug nut cap type hub caps.
Make sure when fitting the new hub cap to the wheel that it fits properly. This is most important for pop-on hub caps that are secured to the rim by plastic tabs and a metal ring. If they seem a little loose fitting, too easy to take on and off by hand, chances are they're going to separate from the rim when you're driving over a bump or other adverse driving conditions. If they fit too tightly, consider having to remove them and if any damage will be inflicted on them when doing so. Hub caps should fit tightly to the rim, but you don't want to be cracking the plastic with a pry bar trying to remove them.
Affix the replacement hub cap(s) to the vehicle in the same fashion it was removed and remember to check it for tightness the first few times you drive the vehicle.