What Does 235/45R18 94V Mean? Tire Size and Load Rating Explained

Every character on a tire sidewall is a specification, and 235/45R18 94V carries five of them. Read it left to right and the string tells you how wide the tire is, how tall its sidewall sits, which wheel it mounts to, how much weight each corner can carry, and how fast it is approved to spin. The fifth piece matters most when you shop, because two tires with identical 235/45R18 sizing can still carry different load and speed ratings — and only one of them may match what your vehicle actually requires.

How Do You Read 235/45R18 94V?

The code breaks into five parts, and each one answers a separate question about the tire.

• 235 — section width in millimeters, measured across the tread at its widest point.
• 45 — aspect ratio, meaning the sidewall height is 45% of the 235 mm width, so roughly 106 mm.
• R — radial construction, the standard build for passenger tires today.
• 18 — the wheel diameter in inches, per Pirelli’s size-page explanation of the format.
• 94V — load index 94 paired with speed rating V.

Those last two figures carry the real-world consequences. Pirelli’s size page lists 235/45R18 94V as a size it builds, and Pirelli’s product page for the P ZERO ALL SEASON in this exact size confirms load capacity index 94 and speed category symbol V, rated at 240 km/h. The load index is the maximum weight each wheel can support, and the speed rating is the maximum approved speed — both defined that way on Pirelli’s own size page.

What Do The 94 And V Ratings Actually Mean?

Multiply the load figure by four and a set of these tires is rated to carry about 5,908 lb — but that is a ceiling figure for the tire itself, not a target for your car. The V rating’s 149 mph cap has nothing to do with how fast you plan to drive. Speed ratings describe how much heat a tire can dissipate before its internal structure starts to degrade, and higher-rated tires resist that heat buildup better under load, which is why manufacturers specify a minimum rather than a recommendation.

What Do Shoppers Get Wrong About This Size?

The most common error is assuming any two 235/45R18 tires can swap freely when their load index or speed rating differs.

JustTires states the caution plainly: 235/45R18 is a size designation, not a full fitment guarantee. Overall diameter, load index, speed rating, wheel width, and the vehicle manufacturer’s specs still have to line up. A second frequent mistake is shopping on width and rim diameter alone while ignoring the aspect ratio — the 45 is what sets sidewall height, and it feeds directly into the tire’s overall diameter, which in turn affects speedometer accuracy and clearance.

Then there is the safety side. Fitting a tire with a lower load index or speed rating than your vehicle requires can make it unsuitable for the car, per JustTires’ guidance on load index and speed rating. That is why the door jamb sticker and owner’s manual outrank any internet calculator. If you’re weighing specific models in this exact size, our tested roundup of 235/45R18 94V tires compares real options side by side.

When you do compare, verify the ratings match your vehicle’s required spec before you buy. Pirelli’s product page for this size is a useful reference point — the P ZERO ALL SEASON carries the 94V marks, and Pirelli’s 235/45R18 94V product specifications spell out the load and speed figures for that exact fitment.