You'll notice that Me 109G-1 and most Me 109G-2 had a retractable tailwheel. Weight growth and the resulting enlargement meant that aMe 109 lost its rtractable tailwhell as the airframe was not modified for production reasons. The retractable tail wheel did not come back in till the Me 109K4 in October 44.
As to why it was 'large' is hard to tell, did the 109 put more weight on the wheel.