The concept of climbing ability is different from what we generally understand. It does not mean an angle but means:
Expressed in %, it refers to the ratio of the slope height (H) to the horizontal distance (L). This is the 10% you said. You can imagine a right angle, H = 10 meters, L = 100 meters.
For example, the maximum slope angle on the car is 31°, so the maximum grade is tg (31°) = 60%.
It can be seen that the climbing ability and the slope degree are not a concept. Please pay attention to the distinction, do not confuse, so as not to buy the inappropriate product.