The differences between 17, 18 and 19 inch tyres

Is a 17" wheel more comfortable than a 18" wheel? Does a 19" wheel feel more sporty than its smaller brother? As always with tyres, the answer is yes, no and maybe. Watch the video, or read on for the full information! 

To answer the question of what changes when you change wheel size, we tested three versions of the excellent Goodyear Eagle F1 Asymmetric 3 tyre using a Golf GTI at Goodyear's incredible test facility in Mireval. This facility allowed us to objectively test the tyres in wet and dry braking, straight and curved aquaplaning and wet and dry timed handling, and also allowed objective testing of how the tyre feels during wet and dry handling. We also focused on the all important NVH (noise, vibration and harshness) tests, to see if you really can make your car more comfortable by dropping a wheel size.

The sizes chosen were simple, they're three OE options for the Golf. 225/45 R17, 225/40 R18 and 225/35 R19 all have the same tyre width, and the rolling radius differs by just 0.4% meaning they should have a near identical footprint. As a result, the differences in performances measured will be down to the tyre construction, rather than any other factors.

The Objective Data

With each of the three tyre sizes near identical in footprint, would the raw numbers show any difference in the tyres performance? The short answer is: No, not much.

During dry and wet braking, there was never more than 1% separating the three sizes, with a very similar result during the straight and curved aquaplaning tests.

Braking

The laptime data was slightly more revealing, but not always in the way expected.

During dry handling, the tyres got progressively faster, with the 17" tyre the slowest, the 18" tyre just over a second faster, and the 19" tyre another 2/10ths on top of the 18". In the wet this trend was reversed, with the 19" tyre the slowest by 1/2 second, then the 18" and the 17" the fastest. This is due to the 17" tyres construction allowing more movement in the tread, which meant the water channels and rubber moved around and opened more resulting in extra grip.

Objectively at least, the three tyre sizes were very similar, to the point of being near identical.

The Subjective Handling

With the objective data being so close instead we turn to the subjective handling and feel of the tyre to find the real differences.

Braking

During dry handling, the tyres subjective feel improved with the lap times. The fastest lap time of the 19" wasn't because the largest wheel size offered more grip, it was due to the way the tyre delivered the performance -  the turn-in of the tyre was far sharper and the car felt more responsive mid corner. Where the 17" tyre felt soft and vague, the 19" fed you with confidence and stability, allowing you to hit all your apex point, giving you the information you needed to really push the car. The difference between the 18" and 19" sizes was much smaller than the jump from 17" to 18", but there was still a step.

Braking

To prove the adage that nothing is simple in the world of tyres, the subjective wet handling testing was completely reversed. The confidence and predictability the larger wheel sizes gave in the dry was replaced with nervousness and far quicker loss of grip in the wet. The 17" was a dream to drive, the car planted and predictable, reacting to every steering input as you would expect. When changing to 18" wheels, the cars more focused front end turn-in meant you had to be more careful of the rear, with the car balance changing to oversteer over bumps in corners the 17" just absorbed, meaning you hesitated for longer during quick direction changes.

As with dry handling, the differences between the 18" and 19" wheels was far smaller than the 17" and 18" wheels, with the 19" feeling like it every so slightly extended the issues the 18" size introduced.

Comfort and Noise

With the subjective results giving the 19" the win in the dry and the 17" in the wet, does NVH (noise, vibration and harshness) testing make a conclusion any easier?

Braking

During the 3km road route, we subjectively and objectively measured the tyre noise level, and subjectively scored comfort.

As expected, the 17" tyre was the most comfortable, with the 18" size delivering more of the road bumps into the car, especially at the rear of the car where the tyre has less weight to manage.

As a result of the extra comfort of the 17" wheel, the car felt a little less planted during road handling, with the 17" shimmying over imperfections of the road where the 18" felt more stable, almost as if the car had upgraded dampers on the 18" wheel and tyre combination. Perhaps the biggest surprise was the noise levels, the 18" was a full dB quieter than the 17", and was immediately noticeable in the cabin.

Where the 18" slightly reduced comfort in the cabin, the 19" started crashing, and while the overall noise level in the cabin was the same as the 17", the overall experience of driving the tyre on rough surfaces was far more stressful, as every minor issue with the road surface was amplified into the cabin.

How to Conclude…

Will a 17" tyre offer more comfort than an 18" or 19" tyre? Most likely, yes. Will a bigger wheel size like 19" feel more sporty than a smaller one? Yes. What wheel size was the best overall balance for this Golf GTI? The 18".

Braking

The Golf GTI is a hot hatch, and as amazing as the 17" wheel size was in the wet, it didn't really suit the car's character in the dry.

While the 19" wheel size looked the best and felt much better in the dry, the nervousness in the wet and the comfort levels on the road made driving the GTI hard work, having to respect the limits and avoid any sort of surprise on the road.

The 18" wheel and tyre combination just felt "right". While they certainly weren't as comfortable as the 17" wheel, the penalty in road imperfections was worth the trade for more precise steering and sporty handling in the dry and wet.

If you have a big car like an Audi A6 on 19" wheels and you're looking to improve your comfort, then it's safe to say dropping to a smaller wheel size will help, but at the expense of dynamic handling, but it's also worth keeping in mind you can improve noise and comfort by switching to a different tyre, so it's worth doing your research first.

If you have any questions or comments, please feel free to ask below.

Further Tyre Information




Discussion:

comments powered by Disqus