IF you have a lenient, and understanding, judge you might get it excused. What you will need to do is to beg off because you didn't realize that the larger tires caused the speedometer error. And, here is what happened. The original tires were 28" in diameter or 87.96" in circumference. The new tires are 33" in diameter or 103.67" in circumference`. That caused my speedometer to read low by 15.15%. So when I thought, and my speedometer told me, that I was going 55 mph, I was really going 15.15% faster or 63.333 mph.
Now the key is that the speed you WERE going has to be within the area of error caused by the larger tires. If not, you MIGHT still get that much of it excused and get the ticket reduced.
The other thing is you want to have the receipt, or such for the corrective gear to fix the problem and assure them that you will be able to trust your speedometer in the future and when you are staying within the speed limit you really are.
You see, math in school really is necessary and helpful.
You didn't say what the speed limit was and what you were doing.