Should a "personal" name go to plural?

[Arly]

Hi,

I don't know ow to refer to this kind of names: let's imagine a car has a tire which is called "Roundy" (maybe is its model or its brand). That's the name of a special kind of tires.

Now, I want to refer to this kind of tires. Should Roundy go to plural? Here's an example sentence:

They used 2 distinct Roundy tires, while the others used 6 distinct Roundy.

I assume the first "Roundy" shouldn't go to the plural, but should the second Roundy be Roundys?

NOTE that Roundy isn't exactly an adjective...

Thanks.

[Mister Micawber]

Your assumption is correct:

They used 2 distinct Roundy tires, while the others used 6 distinct Roundys.
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Native English teacher at Mister Micawber's