Tires of the same model but different sizes - how much difference in quality and performance?

Question

ADAC tested winter tires of size 175/65 R14 T and 205/55 R16 H this year (in English: 175/65 R14, 205/55 R16). I would like to buy a set of size 185/65 R15.

Question: Does it make sense to base the decision on the results for the 175/65 R14 size? (Or maybe 205/55?)

In other words, could it happen that a tire that ranks well in those results, performs significantly worse in another size? (Of course, I'm aware that it could get say at place 2, instead of place 1, and that's fine. What I'm really asking is, if it could happen that say a tire that is in the top 3-4 in the size 175/65 could be at the bottom for the size for 185/65, because it is so much worse?)

To put it differently, I'm expecting either an answer along the lines of "yes, the performance of a tire of a given size is a good (enough) indicator of how the same model of different size will perform", or "no, you can absolutely not make conclusions based a tire of a different size".

Remarks:

(In case it matters): what is most important for me is safety (low noise and consumption are nice to have too, but safety is the absolute priority -- i.e. if the tire would get a lower ranking just for higher noise or consumption, I would still consider that.)

I know that the this specific size (185/65) was tested in 2016. Still, the general question is valid (i.e., if we can or not make conclusions based on a tire of the same model, but a different size). Also, this creates a second question: am I better off using the results of 2016 for deciding (which are for the exact same size, but two years old), or the results of 2018 (which are for a slightly different size, but recent)?

Answer 1

Mostly yes, the performance of a tire of a given size is a good (enough) indicator of how the same model of different size will perform.

What you are really shopping for is a particular price point for a particular set of features. Presuming that the tire manufacturer knows what they are doing (a reasonably good assumption, particularly if it is a manufacturer you have heard of before) they will incorporate the same practices (design, materials, manufacturing know-how) across the line.

Not a bad idea, though, to get a second opinion, such as from a site like Tire Rack.

Answer 2

The design of the tire will be very similar through out the size ranges, and should perform similarly. When comparing tires, you want to compare tires of the same size if possible. You are looking more at the differences between 2 models of tires than 2 exact tires. It is best if you can find a back to back comparison, same vehicle, same tire sizes. Overall, as long as the tire doesn't have some negative aspect (poor wet traction, excessive road noise, quick wear rating), I wouldn't be surprised if you would notice much difference between 2 tires at the same price point.

Wider tires will provide more traction in dry conditions, because there is more contact patch with the road. However, skinnier tires are better in wet, snow, and ice as there is more force on the parts that do contact the road.

A taller sidewall will give a smoother ride, as the sidewall can absorb some of the impact of bumps in the road. A shorter sidewall will give better handling as the sidewall will deform less.