Hi abapicaltaenia,
The 2 tymps I own are fiberglass Ludwig's. I have 2 pics of both my kits with the tymps posted on this site. One pic is under The Bonham set thread, the other is under show your Tama's. The stick dings I mentioned are visible if you look closely at the heads. Since tymp heads are much thinner they ding easily with sticks. So while a tymp head played with mallets can last years, I have to replace them much sooner. I have replaced many heads on my tymps because of this.
Presently on my 26" tymp have a "Ludwig Ensemble Reg. Tympani Clear 26"", I measured the diameter of the head and it is 27", not 28". The Ludwig Ensemble head even has 26" printed on it, but the measured head diameter is actually 27". I also have 2 spare new unused Remo tymp heads I purchased, when I ordered them I had to order a 27" and a 30". The 27" Remo is the exact same size as the 26" Ludwig and fits just fine. So I can clearly state the difference is 1 inch and not 2 inches.
I hope this helps Topgun get the correct heads so he/she can go on tour and have fun.
Boomstand