Quick Slicks HR12 tires are designed specifically for H&R 1:24 27x18mm wheels with out a center rib/spike.
For a complete list of cars/wheels this tire will fit, please refer to the Quick Slicks Fitment Summary which is updated on a regular basis.
This is the EXTRA FIRM compound (part number: HR12XF).
Dimensions (Mounted on Wheel):
Outer Diameter (O.D.): 1.10" (28.00mm)
Width (Contact Patch): .650" (16.50mm)