First order of business would be to get yourself a durometer. That is the only way to be certain that you haven't gone too far while making sure you've gone far enough. Make note of the initial reading of each tire.
Next, depending on the product, it's usually the norm to extend the treatment out over several days. Get yourself some old rags or those heavy duty shop paper towels. Use a paint roller (better than a brush) to apply the product, rotating the tire as you go. Initially apply several coats of product directly to the tire, or as directed by the manufacturer. Then, wrap the tire around the circumference a couple times with the paper towels and secure with masking tape or similar. Then soak the paper towels thoroughly with the product and wrap immediately with the paper towels. There should be a resting period of up to one day. Take secondary readings and repeat the process. Continue to repeat until you get about 5 durometer points below your target number (which for Toyos I would guess is around 55). Once you get to 50, you would cease the treatment and keep the tires completely wrapped until you are ready to use them. The durometer reading will rise during the resting period.
Note: Sometimes you have to deviate from the label instructions to get the best results.
