You will never be sure until you do exactly that.
There are about 7 different 6-lug bolt patterns between 6x4.5 and 6x5.5. And, even if you have the same bolt pattern, you may have problems interchanging them due to offset. In other words, it's too close to diagnose over the internet. Even if someone knowledgeable answers your question, you still need to verify it.
This is a pretty knowledgeable and helpful crowd around here, but I wouldn't recommend accepting the opinion of some random guy on the internet (like me) that won't be there to help when you find out that your spare doesn't fit.
Dexter does offer a bolt pattern that will match your Taco, but the only way to be sure your spares are interchangeable is to try and see.