Some of the reviews in this page are not accurate so here are the basic facts about Tawhitokino beach:
This is generally a safe, shallow beach with reddish brownish sand - but nothing special - just a normal beach.
Ocean tides do not affect the road at all, so you can drive when it is high tide or low tide.
However, it is not worthwhile going there in long holiday times because of the huge number of people and vehicles heading there. I really don't get it why so many people flock into this cramped up beach in droves!!
The access road is narrow and winding, so it is challenging to drive as it is a 'single lane' status most of this 4km stretch from the Kawakawa boat ramp. Parking area at the beach area is very limited, to about 20-30 vehicles, and because of the narrowness of the road it is hard to do roadside parking either. On long weekends and any holiday in the summer it is a chock-a-block and you may not find a single place to park so it is highly advisable to avoid such days because turning and getting back to Kawakawa would again be challenging to give way to oncoming vehicles.
Also, when it rains, it's quite frequent to get earth slips limiting access to the end point.
BTW, there are many other very nice, shallow beaches in Kawakawa area with heaps of parking spaces.