Sorry to disagree here but the answer to this is no. Yes, it may say on the sidewall of the tire that it is a 275/30/19, but the actual size of the tire varies by tire manufacturer. No tire is identically the same size no matter what the sidewall says! You can put every single 275/30/19 tire on the market right next to one another in a straight line and you will see the differences. You'd actually be amazed by how much difference there is.
To the OP, the Maragoni tires are one of the taller sidewall tires on the market in a 30 series.
Originally Posted by Yukon Dave
Back to the original question, "Is 30 all the same in all tires brand".
Yes it is always the same but it does not mean 30mm or any other fixed size. It is the aspect ratio. So its height depends on the width of the tire.
265 is the width in milimeters, 35 is the aspect ratio and 18 is the wheel diameter in inches without the tire.