No luck in finding definitive proof that the He-177 tail wheel was used as the nose gear wheel on the 229 but the link below shows the size of the He-177 tail gear minus the wheel. Quite a beast.
http://aviationarchaeology.co.uk/wp-...9/He177-41.jpg
The tire size for the Horton is shown as a Continental 1015 X 350 in drawings.
Hope this helps.
Vince...