To determine how many cars can get new tires, we first need to find the total number of tires from both shipments.
The first shipment has 16 tires, and the second shipment has 8 tires.
Calculating the total number of tires:
\[ 16 \text{ tires} + 8 \text{ tires} = 24 \text{ tires} \]
Next, we know that 4 tires are put on a car at a time. To find out how many cars can get new tires, we divide the total number of tires by the number of tires needed for one car:
\[ \frac{24 \text{ tires}}{4 \text{ tires/car}} = 6 \text{ cars} \]
Therefore, 6 cars can get new tires.