How to Choose 245/40R17 Tires | The Three Fitment Rules

Choose 245/40R17 tires by mounting them on 9-inch wheels, selecting Y or W speed rating, and fitting them only on staggered rear axles.

How to choose 245/40R17 tires comes down to three rules most first-time buyers miss. Wheel width, speed rating, and axle placement determine whether the tires perform as intended or become a handling liability. Get these three right and you can safely pick among the top models from Goodyear, BFGoodrich, and Ventus.

What 245/40R17 Actually Means

The size code carries everything a tire shop needs. 245 is the section width in millimeters. 40 is the aspect ratio — the sidewall height equals 40 percent of the width, giving a 3.86-inch sidewall. R stands for radial construction, and 17 is the wheel diameter in inches. The total diameter comes out to 24.7 inches with a circumference of 77.6 inches and 816 revolutions per mile.

That low 3.86-inch sidewall delivers sharp steering response and stable cornering, but it also transmits more road harshness than a taller sidewall would. This profile suits performance cars well; it is less forgiving on rough pavement and potholed roads.

Which Wheel Width Works Best for 245/40R17?

Mount 245/40R17 on a 9-inch wide wheel for optimal performance. The officially approved range runs from 8 to 9.5 inches, but the 8-inch end sacrifices tread contact and sidewall support. Experienced owners and installers consistently recommend 9 inches as the real minimum.

A 9-inch wheel keeps the tread flat against the road during cornering and hard braking. On an 8-inch wheel the sidewall pinches inward, shrinking the contact patch and accelerating shoulder wear. The difference in grip and tire life is immediate and measurable. If your current wheels measure 17×8, the tires will technically mount but the handling trade-off is noticeable.

Speed Rating: What’s the Difference Between Y and W?

Y-rated tires survive sustained speeds above 186 mph and belong on high-performance vehicles like the BMW M3 or Mercedes-AMG. W-rated tires cap at 168 mph, which covers most sport sedans and coupes without overbuilding for speeds you will never reach.

The Goodyear Eagle F1 Asymmetric 6 carries a Y rating at $235 per tire. The BFGoodrich 91W carries a W rating at $219. Match the rating to your car’s actual capability — a W-rated tire on a car that exceeds 168 mph risks structural failure, while a Y-rated tire on a daily commuter adds cost without providing any real benefit.

Tire Models Compared

For a detailed comparison of the best options available, check our tested 245/40R17 tire recommendations.

Staggered Fitment: Why This Size Usually Goes on the Rear Only

245/40R17 is almost always a rear axle size in staggered setups. Cars like the BMW Z4 and Mercedes C-Class run a narrower front tire — typically 225/45R17 — and step up to 245 on the rear. This widens the rear contact patch for better traction under acceleration and gives the car a more planted stance.

Do not put 245/40R17 on the front axle of a staggered car unless the manufacturer explicitly approves it. The wider tire can rub suspension components during turns and alter steering geometry. If your car uses the same size on all four corners, you can run 245/40R17 front and rear without issue.

Picking 245/40R17 Tires: Common Fitment Mistakes

The three most frequent errors people make with this tire size cost either money or safety.

Using 8-inch wheels. An 8-inch wheel sits at the bottom of the approved range. It works in theory but produces weaker cornering grip and faster shoulder wear. Most experienced owners steer clear and move to 9-inch wheels.

Ignoring the speed rating. Slapping a W-rated tire on a track-capable car or a Y-rated tire on a family sedan wastes performance or money. Know your car’s top-speed capability before you choose.

Assuming all 245/40R17 tires fit identically. Tread width and sidewall shape vary slightly between brands. A tire that fits a 9-inch wheel from one manufacturer may sit differently on the same wheel from another. Always check the tire’s spec sheet for its measured rim width range before buying.

245/40R17 Technical Reference

How to Verify Fitment Before Buying

Start by measuring your current wheel width. Look for the stamp on the back of the spoke or inside the barrel. If it reads 17×8, the tires will mount but expect reduced performance. If it reads 17×9 or 17×9.5, you are in the optimal zone.

Next, check your vehicle’s original equipment size. For staggered cars, confirm the front and rear sizes separately. As Tire Rack’s fitment guide shows, most vehicles using this size specify it for the rear axle only.

Finally, account for the 3.8 percent diameter difference if you are replacing a 245/45R17 set. The shorter 245/40R17 turns more revolutions per mile, which the speedometer reads as a higher speed than actual.

Final Fitment Checklist

• Verify your wheel width is 9 inches or wider for optimal handling
• Select a Y or W speed rating that matches your car’s performance envelope
• Confirm the tire goes on the rear axle in staggered setups
• Measure clearance for suspension and fender clearance on lowered cars
• Compare the revs-per-mile against your current tires to anticipate speedometer shift