The thickening from the inside is based on the fact that the steering wheel rim receives a greater extent from the inside out, but without increasing the overall circumference of the steering wheel. This modification requires a high level of skill and requires a lot of work and time. The result is incomparable. Let us convince you with an example.
Photo 1. As an example, here is an ordinary VW Golf 6 steering wheel with a diameter of about 37 cm.
Photo 2. The steering wheel rim is almost 10 cm thick.
Photo 3. After our modification, the steering wheel rim is 11.5 cm thick.
Photo 4. But how much is the overall diameter of the steering wheel? Still 37 cm! The steering wheel rim will be thicker and grippier, but the steering wheel in total not bigger!