Hello and thank you for trusting us with your question. I'm DJ.
The three most popular differentials in Toyota trucks are 4.11, 4.30 and 4.88. So you're probably right on with your count at 4.10.
I've had 31" tires with 4.30 gears and it wasn't a screamer, but I could do much better than 50 without a problem. What transmission do you have? Can you tell me what your RPM is at any given speed? Like 1500 RPM at 60 in 4th gear? We can calculate what the exact ratio is if we know what gear it's in, what the RPM is and what the speed is.
Have you tried advancing the timing to see if it pings? It's not common, but it happens where the ring on the front crankshaft pulley turns. So if you set the timing to factory specs, the timing is actually retarded. It happened on my 1987 truck. I had to set the timing to 18 degrees to get it to run good and it didn't ping.
Easy enough to test, try it and see what happens. If this in fuel injected, make sure you have a jumper between TE1 and E1 in the DIAGNOSIS box when setting the timing.
Next I would check the cam timing to make certain that the cam isn't retarded. This will really kill power.
Check these out in this order. We may have to do more testing, but we have to start someplace and these are the most common culprits.
Please let me know what you find.