| Spec | Old | New | Diff |
|---|---|---|---|
| Diameter | 634.5 mm | 631.9 mm | -2.6 mm |
| Revs/km | 502 | 504 | 2 |
This tire size is within the safe range. Your handling will remain stable.
When your speedometer shows 100 km/h, you are actually traveling at 99.59 km/h.
Welcome to the workshop! I’m glad you stopped by. If you’re looking to upgrade, downgrade, or just better understand the rubber connecting your car to the asphalt, you’ve hit the right spot. As a tire engineer, I spend my days obsessing over compounds, tread patterns, and—most importantly—dimensions. Today, we’re pitting two extremely common, yet fundamentally different, tire sizes against each other: the classic 195/65 R15 and its slightly sportier cousin, the 205/55 R16.
It might only seem like a few numbers change, but those subtle shifts dictate everything from how comfortable your commute is to how much petrol you use. Let’s break down the engineering reality of this switch.
Before we discuss performance, let's quickly define the players. This is crucial for understanding the trade-offs.
The core difference here is the profile. Tire A has a high-profile design, offering more air volume. Tire B has a low-profile design, maximizing rim size and reducing sidewall flex.
When changing tire sizes, maintaining the overall rolling diameter is essential for vehicle safety, traction control calibration, and, most importantly, accurate speed readings. Thankfully, these two sizes are engineered to be extremely close replacements, often used as base and optional upgrades by manufacturers.
Let's look at the math (I promise to keep the equations brief):
The difference is only about 2.6 mm, meaning Tire B is just 0.41% smaller than Tire A.
What this means for your dashboard: Since Tire B is negligibly smaller, your wheels must rotate fractionally faster to cover the same distance. If your speedometer reads 100 km/h with Tire A, it will read approximately 100.41 km/h with Tire B. This difference is so minute that it is completely negligible and won't affect compliance or safety. If you were swapping to a significantly different size, this math would be critical, but in this case, the manufacturers did their homework!
This is where the rubber truly meets the road. The performance trade-offs are dictated almost entirely by the sidewall height and the tread width.
Tire A (195/65 R15) boasts that tall 65-series sidewall. Think of that sidewall as an extra air spring. When you hit a pothole, expansion joint, or rough pavement, that generous cushion absorbs the vertical shock before it reaches the suspension. If your driving involves poorly maintained urban roads or long highway cruises where comfort is paramount, Tire A is the clear winner.
Tire B (205/55 R16) is designed for responsiveness. The shorter 55-series sidewall resists lateral distortion (sidewall flex) under aggressive cornering. When you turn the wheel, the tire reacts immediately, giving you a far more connected and precise feel. Furthermore, the 10mm extra width translates into a larger contact patch, increasing overall grip and braking performance, especially in dry conditions. If you enjoy spirited driving or need maximum cornering stability, Tire B delivers superior dynamic handling.
When considering running costs, we look primarily at rotational mass and rolling resistance (RR). Generally, two factors determine efficiency:
Because Tire A (195/65 R15) is narrower and usually mounted on a lighter, smaller rim, it will consistently offer better fuel efficiency compared to Tire B. The difference might only be 1% to 3% in real-world scenarios, but over the life of the car, it adds up. If minimizing fuel consumption is your top priority, stick with the 195/65 R15 setup.
As always, there is no single "best" tire size; only the best size for your specific mission. Think about your daily commute and prioritize accordingly:
Ultimately, the switch from A to B is a classic engineering trade-off: trading a marginal amount of fuel efficiency and ride comfort for a significant gain in steering response and dynamic ability. Choose wisely, drive safely, and remember to always keep those pressures correctly set!