What size tire chains do I need?
Type the code off your sidewall. It tells you what to order, what each number means, and the one thing to check in your manual first.
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Chains are sold to fit a range of tire size codes, not a range of vehicles. Two trim levels of the same model in the same year can take different sizes, and shopping by vehicle name is the single most common way people order the wrong thing.
So this tool does one thing: it reads your sidewall code back to you, explains what each part means, computes the overall tire diameter from it, and hands you the exact string to match against a manufacturer’s fitment chart.
Read your sidewall
Type the code molded into the side of your tire. It looks like 225/65R17 and it is on the outer sidewall of every tire on the car. Do not use the size on a parts website, and do not use the size the car came with from the factory if someone has since fitted something else — use what is physically on the wheel right now.
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Order chains to fit
225/65R17
That exact string is what you match against a chain manufacturer’s fitment chart. Chains are sold to fit a range of tire sizes, not a range of vehicles.
- Section width
- 225 mm
- Aspect ratio
- 65%
- Rim diameter
- 17 in
- Overall diameter
- 28.5 in
The sum: sidewall height = 225 × 65/100 = 146.3 mm. Overall diameter = 17 + 2 × (146.3 / 25.4) = 28.5 inches.
Before you order anything
Check your owner’s manual first. Vehicle manufacturers publish the clearance available around each tire, some specify “low-clearance” or SAE Class S chains only, and some prohibit chains on certain axles or entirely. A chain that fits the tire and not the car will destroy a wheel arch, a brake line or a suspension component. The tire code above tells you what size to buy; only the manual tells you whether you may.
What to buy, given all that
Security Chain Company
Security Chain Company Super Z6 Cable Chains
Roughly $70-$120 a pair
A low-clearance cable chain, which is the type most modern cars actually need. The clearance requirement is the entire buying decision here and most people never check it: many vehicles do not have room for a conventional link chain in the wheel well.
Skip it if: Your owner's manual prohibits chains on your vehicle, or specifies a clearance you do not have. Check the manual before you check the price.
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AutoSock
AutoSock Textile Snow Sock
Roughly $80-$150 a pair
A textile cover that pulls over the tire. It fits vehicles with no clearance for chains, takes about a minute a wheel, and is the option that is accepted in some places where chains are not - which is worth checking before you buy either.
Skip it if: You need traction repeatedly over long distances. Textile wears fast on bare pavement.
#ad We hold no verified live price for this product, so we show none. How this site is funded.
Where to find the code
It is molded into the outer sidewall of every tire, in raised lettering, and it looks like 225/65R17 or P225/65R17 or LT265/70R17.
Read it off the tire itself, in daylight, with a torch if necessary. Do not use the size on the door-jamb placard if the tires have been changed, do not use what a parts website says your car came with, and check all four — staggered setups with different front and rear sizes exist and they matter here.
What each part means
| Part | Value | What it means |
|---|---|---|
| 225 | Section width | The tread width in millimeters, measured sidewall to sidewall. |
| 65 | Aspect ratio | The sidewall height as a percentage of the section width. Here, 65% of 225 mm = 146 mm. |
| R | Construction | Radial. Almost every modern passenger tire is radial. |
| 17 | Rim diameter | The wheel diameter in inches. Note that this one is imperial while the others are metric. |
A leading P means P-metric, a passenger car tire. LT means light truck, which carries a higher load rating and often needs a different chain. The tool accepts both.
Overall diameter, and why it is here
The formula
Sidewall height (mm) = section width × aspect ratio / 100
Overall diameter (in) = rim diameter + 2 × (sidewall height / 25.4)
For 225/65R17: sidewall = 225 × 0.65 = 146.25 mm. Overall diameter = 17 + 2 × (146.25 / 25.4) = 28.5 inches.
Chain fitment charts are organized by size code, so the diameter is not what you order by. It is here because it lets you sanity-check a chart entry, and because two different codes can produce nearly identical rolling diameters — which is why some chains list several sizes as compatible.
The check that comes before all of this
Your owner’s manual. It publishes the clearance available around each tire, and it will say one of three things: chains permitted with a stated clearance, low-clearance or SAE Class S chains only, or chains not permitted.
That is not a formality. A chain that fits the tire but not the car will contact a strut, a brake line or the inner wheel arch, and it will do it at the first rotation.
If the manual restricts you to low-clearance devices, cable chains or textile socks are where to look.
Common sizes, worked
| Tire code | Sidewall height | Overall diameter | Typical on |
|---|---|---|---|
| 205/55R16 | 112.8 mm | 24.9 in | Compact cars and hatchbacks |
| 225/65R17 | 146.3 mm | 28.5 in | Mid-size crossovers |
| 235/45R18 | 105.8 mm | 26.3 in | Sport sedans, low profile |
| 265/70R17 | 185.5 mm | 31.6 in | Full-size trucks and large SUVs |
Note the third row. A low-profile 18-inch tire has a smaller overall diameter than a 17-inch tire with a tall sidewall, which is the sort of thing that catches people who reason from wheel size.
Then do the practice fitting
Once they arrive, fit them in the driveway on a dry afternoon. That is when you find out whether they actually fit your car rather than just your tire, while there is still time to return them. The chains we would buy are here.
How this was ranked
Every site in this category says it tested twenty of these. We have not tested any, and we say so. What we did instead: built the candidate set from what Amazon actually stocks, compiled the published specifications from each manufacturer’s own pages, did the arithmetic on running cost and on what the thing prevents, and read owner reviews for failure patterns rather than star averages. Every number on this page has a link to where it was published, so you can check the work.
- Units we claim to have tested
- 0
- Sponsored placements
- 0
- Free products accepted
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Frequently asked
What size snow chains do I need for my car?
Match them to the tire size code molded on your sidewall, for example 225/65R17 — not to your vehicle model. Read it off the tire itself, then check that code against the chain manufacturer’s fitment chart, and check your owner’s manual for the clearance requirement first.
Where do I find my tire size?
Molded into the outer sidewall of the tire, in raised lettering. It is also on the placard in the driver’s door jamb, but that shows the size the car left the factory with — if the tires have been changed, only the sidewall is authoritative.
Can I use the same chains on a different car?
Only if the tire size code is compatible and the second vehicle’s manual permits that type of chain. Same size code plus permitted clearance means yes. Same vehicle model but a different trim with different wheels frequently means no.
What does 225/65R17 mean?
225 is the tread width in millimeters. 65 is the aspect ratio — the sidewall height is 65 percent of 225 mm, so 146 mm. R means radial construction. 17 is the wheel diameter in inches. Together they give an overall tire diameter of about 28.5 inches.