It's much easier and cheap to maintenance a wheeled vehicle than a tracked one. Also one advantage of wheeled is higher road speed. Both are good advantage for a QRF unit which need to maintain high alert all time and redeploy fast after activation.
I know that the maintenance and overall procurement cost for the truck system is usually cheaper. Truck based system was developed as basically a compromise of gaining SP's ability to go in (and out) of action quickly, while trading off crew protection and terrain mobility for minimal cost. However, I think that the way the gun is outfitted as shown probably negates a lot of the cost advantage. Radar alone cannot be cheap.
I will be honest, I am not familiar with PLA artillery orbat.
Most NATO artillery orbat is very simple either, an 155mm SP gun like M109 (or CESAR for a truck example), heavy 155mm towed gun (i.e. M777), 105mm light towed gun. If you want to count it, 60mm and 81mm mortar (usually part of infantry).
So many kinds of PLA systems exist, 155 SP tracked (PLZ-05), 155mm towed (AH-4), 152mm towed, 130mm towed, 120mm gun-mortar (PLL-05), etc. etc. Now there is this 155mm SP wheeled as well. Originally it seemed like AH-4 would be best suited for rapid deployment (air transportable by Y-8 or Z-18), but now you have this SH-5 as well, which adds yet another layer of complication on orbat.