I have several dirt people friends and they recommend not even trying to grow grass under trees because of the light issue. Grass, regardless of whether it is labeled as “shade tolerant” or not will not grow without sunlight. Your energy time and money might be better spent planting ground covers under the tree like monkey grass or vinca-not the flower vinca but the ground cover vinca.
Just my 2 cents. Good luck.
It was rightly_dividing that was inquiring about grass under the trees. I have a nice lawn under my trees, but you have to have the trees trimmed to provide light.