Shubova the dia is 4" "Robart low bounce model aircraft scale wheels", is on the front of the package. Upper right corner is a sticker that has " Scale Straight Trd. 4" Dia 118

They come with smooth hub cap for p-40, AT-6 and similar . Spoked hub cap for P-51, corsair and similar.

When I received the new tires I did a bounce test by throwing them hard on the ground. The Robarts were a lot better. The GP tires bounced almost like a Super Ball.

I Had told GP that I had seen other guys that were able to get new tires from them because the GP tires were so bouncy. I told them that I had read it on RC Universe.

I hope this helps.