How to Measure for Tire Chains
Tire chains are useful devices that can make sure a vehicle keeps traction in rough weather. They are popular in snowy, icy climes or in conditions that otherwise threaten the driver's ability to control the vehicle. Tire chains are made to fit a specific range of tire-size, though, and you'll need to know what measurements matter if you plan to install one yourself.
What you'll need:
Measuring tape or ruler (optional).
- Familiarize yourself with tire code. American tire code calls out measurements in ###D###Wr## fashion, such that D is the total diameter of the tire, W is its tread width, and r is its rim diameter. Metric tire-code calls out ###W##Ar##, such that W is the tread width and A is the 'aspect ratio', or the height of the sidewall compared to the tire width. Knowing these formats is important because they are what you will use to purchase the right kind of tire chain.
- Check your tire sidewall. If you're lucky, you won't have to do any measuring yourself. Many sidewalls come with the information of the tire printed straight onto them, and you'll be able to buy an appropriate tire chain based on that alone.
- Measure your tire manually. If your tire for some reason does not have this side-wall information, you should take your ruler/tape and acquire the above measurements yourself. Sidewall height (distance from rim to tread), tread width, and overall diameter are what you should be looking at.
Remember that a tire chain should always match your tire's width, but does not necessarily have to match total diameter. Many tire chains can be adjusted by removing chain segments until they fit the required diameter, and so a slightly-too-large chain can still work on your vehicle. Discuss the matter with the dealer on the specifics of adjusting your tire chain.