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Tire Buying Guide
Buying tires is straightforward once you understand the numbers and the trade-offs. This guide explains tire sizes and ratings, how tire types differ by use, when replacement is due, and how to budget the whole job.
Direct answer
To buy tires, start with the size and ratings your vehicle requires, found on the tire sidewall or the door-jamb placard. Match the size, load index and speed rating at least, never lower. Choose a tire type to suit how you drive — all-season for most, winter for cold climates, performance or all-terrain for specific needs — and budget for mounting, balancing, valves, TPMS service and disposal, not just the tires.
Before you begin
Before you shop, confirm your required size and ratings. Find the sequence on your sidewall, such as 225/45 R17 91V, and compare it with the door-jamb placard and your owner’s manual. Note your driving conditions, your typical mileage and whether you tow or carry heavy loads. Set a realistic budget for the full job rather than the tire price alone.
Step-by-step guide
Start with the numbers
Every tire carries a size and a service description that tell you exactly what it is. The size looks like this: 225/45 R17. The 225 is the section width in millimetres — how wide the tire is. The 45 is the aspect ratio, meaning the sidewall height is 45 percent of the width. The R indicates radial construction, and 17 is the rim diameter in inches.
After the size comes the service description, such as 91V. The 91 is the load index, a code for the maximum weight one tire can carry, and the V is the speed rating, a code for the maximum speed it is designed for. Your vehicle manufacturer specifies minimums for both, and replacements should meet or exceed them. Our load and speed rating lookup decodes these values.
Match the specification, never go below
The single most important buying rule is to match the required load index and speed rating, or better them. A lower-rated tire is not a safe saving; it can reduce the vehicle's safe load and high-speed capability, and in some cases affect towing. Confirm the requirements in your owner's manual or on the door-jamb placard before you shop.
Choose a type for how you drive
Tire types are built around different priorities. All-season tires suit most drivers in temperate climates, balancing grip, comfort and life. Winter tires use softer rubber and deeper tread to keep grip in cold, icy and snowy conditions — a marked improvement over all-seasons below around forty degrees. Summer and performance tires favour grip and handling at the expense of comfort and longevity. All-terrain and highway-terrain tires suit trucks and SUVs, chosen by how much off-road use you actually do.
Do you tow or carry heavy loads?
If you tow a trailer or regularly carry heavy loads, the load index and construction matter more than the tread pattern. Ensure the tire's load index covers what you are asking it to carry, and adjust pressures for the load as your manual specifies.
Know when replacement is due
Tires are replaced for three reasons: tread wear, damage and age. Tread reaches a legal minimum at two thirty-seconds of an inch, but wet grip falls away well before that, so many manufacturers recommend replacing at four. Structural damage means immediate replacement. Age matters too — rubber hardens over time, and many manufacturers recommend replacing tires around six years old regardless of mileage. Our repair versus replacement guide helps if you are weighing a repair.
Safety first: Never fit a tire with a lower load index or speed rating than your vehicle requires. It is one saving that can cost far more than it saves.
Budget the whole job
The price on the tire is only part of the cost. Fitting adds mounting the tire on the rim, balancing the wheel, often new valve stems, a TPMS service when the vehicle is equipped, and a fee to dispose of the old tires. Some shops bundle these; others itemize them. Ask for the full fitted price so you can compare quotes fairly, and use our tire change cost calculator for a rough planning figure.
After the purchase
New tires deserve care from day one. Check their pressures soon after fitting, keep them correctly inflated, and rotate them on schedule to even out wear. A little maintenance protects the money you have just spent and keeps the whole set performing predictably — see our tire maintenance guide. And if a size or fitment question lingers, our tire size calculator shows exactly how a change would measure up.
Mistakes and warning signs
These buying mistakes cost money and, in the worst cases, safety.
Buying a lower load or speed rating
A cheaper tire with a rating below the manufacturer's requirement is not a bargain; it can compromise safety and towing capacity. Match or exceed the spec.
Choosing by price alone
The cheapest tire may wear faster or perform poorly in the wet. Balance price against expected life and the conditions you drive in.
Ignoring the full fitted cost
Mounting, balancing, valve stems, TPMS service and disposal add to the tire price. Budget the whole job so the final bill is no surprise.
Mixing sizes or types inappropriately
Fitting mismatched tires across an axle can upset handling. Follow the manufacturer's guidance on how tires may be mixed.
Buying without checking age
New-looking tires can be old stock. Check the DOT date code so you are not paying new prices for aged rubber.
Tire type by driving need
A general guide to which tire suits which use.
| Driving need | Suitable type |
|---|---|
| Everyday driving in mixed conditions | All-season tires suit most drivers in temperate climates. |
| Cold winters with ice and snow | Winter tires give markedly better grip in low temperatures. |
| Spirited driving or sporty vehicles | Summer or performance tires trade comfort and life for grip. |
| Trucks, SUVs and light off-road use | All-terrain or highway-terrain tires, chosen for your use. |
| Towing or heavy loads | Adequate load index and reinforced construction matter more than tread pattern. |
Tire buying checklist
- ✓Find your required size on the sidewall and the door-jamb placard.
- ✓Record the load index and speed rating and treat them as a minimum.
- ✓Decide your tire type based on climate, driving style and vehicle use.
- ✓Check the DOT date code on any tire you are offered.
- ✓Ask for the full itemized fitted cost, including valves, TPMS and disposal.
- ✓Confirm the replacement interval and any warranty terms before you buy.
- ✓Plan a rotation schedule to protect your investment.
Related tool
Compare a new size against your current one before you commit.
See how diameter, width and the speedometer change.
Questions readers ask
Short, accurate answers to the questions this topic raises most often. These are answers, not a promise of any search feature.
A size such as 225/45 R17 means a section width of 225 mm, an aspect ratio of 45 (sidewall height is 45 percent of the width) and an R17 radial rim of 17 inches. A load index and speed symbol, such as 91V, follow.
You can fit an approved alternate size that keeps the overall diameter and clearance within safe limits, but you should follow the manufacturer's guidance and keep load and speed ratings adequate. A size calculator helps you compare.
Replace on tread wear, damage or age. Many manufacturers recommend replacement at around six years and inspection from about five, regardless of mileage, because rubber ages.
If you regularly drive in cold, icy or snowy conditions, winter tires markedly improve grip. In mild climates, a good all-season tire is usually adequate.
Fitting adds mounting, balancing, valve stems, TPMS service and old-tire disposal. Ask for the itemized fitted price so you can compare quotes fairly.
Related resources
Confirm replacement is really needed.
Protect your new tires from day one.
Estimate the fitted cost of new tires.
Part of Tire Buying. Browse all tire guides.
Sources and references
- National Highway Traffic Safety Administration (NHTSA) — Tires
- Your vehicle owner's manual — required tire size, load and speed ratings
- Tire manufacturer guidance — tire types, ageing and warranty terms
This guide is general information maintained by the TireHelpGuide editorial team. It links to primary sources above and is not a substitute for your vehicle and tire manufacturer’s guidance or a professional inspection. We do not publish a reviewer name or review date until a qualified reviewer can be verified.