Yes, this product is totally safe for your tires, wheels, coated engine and aluminum. All we recommend is to follow the instructions such as don't use on hot wheel/brake/engine components, and to give it a good and thorough rinsing and drying afterwards.
I would also highly suggest taking a look at our CarGuys Hybrid Wax. This would work perfectly on your Harley as it is completely safe to use on every part of the bike.