Rated for 16" wheels, up to 4000 lbs. What is your permissible total weight? Many modern cars use large wheels with low profile tires, in contrast to last year's cars which used smaller wheels and larger tires. Are you sure with some hinged pieces of metal less than half a gallon of milk? It's an A-frame design and the triangles have a lot of power. The engineer can calculate and account for the true tolerances for that item. To me, this is better than simply using a random piece of wood that may or may not be readily available at the side of the road. Practice safe lifting. On standard US 1/2 ton trucks, stopping in gear uphill or in "P" and applying the parking brake will prevent the rear drive wheels from spinning. give parking brakes. In this case you have more problems, this wedge will solve it. But it's even more important to have the wheel chock handy to keep your truck from rolling away. To be on the safe side, I support the rear and then lift the front part first. After the front is safely jacked up, I lift the rear. If you're wondering why someone would lift their entire car off the ground when the car's weight is on jack stands, then you don't need these wheel chocks. You only need a mobile phone to call for help. Many trailers use smaller wheels and tires, and here you will use them. Imagine a flat platform hauling a motorcycle or landscape debris. What is the weight of your loaded trailer, like your car? This item is suitable for small cars. As pickup trucks and SUVs get bigger, weigh more, and run on bigger wheels and tires, I'd play it safe. How often do you have to put upholstery in your car? Every time you jack up your car you have to block the opposite wheel. When you lift the front driver's side, lock the rear passenger's side. Check out this product. This isn't something you will use long-term. This is something only for emergencies or when traveling. Let's say you need an extra measure of roadside safety when you lift a wheel to replace a flat tire. Or after you've launched the boat and parked the empty trailer. You may leave a trailer with tools and a work team in a remote location. Don't think of this as the block you use when storing your boat on a trailer or car. In the old days you just found a piece of wood that you are not using and then some air from the tires so that the weight rests on this block of wood. How many people have extra wood in today's world? Or even have an air compressor to pump up that tire later when you need to move the car or trailer again? We used to have motorcycles and rode them. Now people bring their bikes to events just to show them off. We used to drive our cars every day, then we would go to the track and race. Today people stock cars that they tow on trailers. This is not a problem. Everyone should have at least 2 of these kits in case of unforeseen circumstances. Take them to the dealer next time you buy a car and only buy the car they fit. You don't want to reinvent the wheel. When buying a new car, make sure you can take advantage of them. Don't do it like me. For big, heavy trucks and big tires, I put 2 wheel chocks next to each other. Do math. Bend the numbers. Try not to kill yourself by using them in a way not recommended by the manufacturer. Although I'm still alive.