I cannot find specific rules for planting tree at road allowance in Toronto. Can I plant my own tree which is not from https://www.toronto.ca/data/parks/pdf/trees/street-tree-brochure.pdf such as different variety (not listed) Fagus Sylvatica Tri-Color (European Beech)? I believe it was required before trunk diameter to be 4cm, not fruiting, etc.; but I cannot find these anymore. Are regulations changed?
I looked carefully through the City of Toronto website, Tree Planting and Tree Planting Strategy sections, and I couldn’t find specific answers to your questions. I emailed Toronto Urban Forestry at email@example.com with your specific question and after 5 days, I hadn’t received a reply. You could try emailing as well. They give no phone number, but there is an address: 18 Dyas Road, Toronto, ON M3B 1V5.
I think the lack of guidance for trees purchased by homeowner means that you can plant whatever species you like on the road allowance if you are paying for the tree. All the restrictions on tree species only apply if the city is providing the tree for your front yard free of charge or if you are using some low cost organizations such as LEAF
or Tree For Me https://www.treeforme.ca/
European beeches grow to a large size – 70′ tall by 40′ wide and they are shallow rooted. If they are planted close to the sidewalk, the roots may eventually buckle the sidewalk which will trip people up and likely make the City unhappy. You also need to make sure your front yard is large enough for such a large tree.