Here are the part numbers for the Paul Gage tires from Slot Car Corner.
PGT-17080SM – 17mm diameter, shore 40, harder
XGP-17080SM – 17mm diameter, shore 20 softer
PGT-18080SM – 18mm diameter, shore 40, harder
XGP-18080SM – 18mm diameter, shore 20 softer
I think it would be best to use the 17mm diameter but don’t know for certain without trying both. Maybe Marc can add some additional information to this discussion.
Marty