Formula for correcting odometer error?

I'm considering going a bit larger on my tire/wheel size, and was wondering if there is an easy math formula to calculate my odometer error, if I know the speedometer error.
For example: my stock tire size is 215/70/15 (26.9"), and I may go to a 225/70/16 (28.4"), which would give me a speedo error of 5.8% (a 60 mph reading on my speedo would now actually be 63.5 mph), courtesy: I just want to be able to calculate gas mileage accurately.
If I multiply my odometer reading X the % error (.058), then ad that to original reading, I should get the correct mileage . . . right?!
For example: trip odometer reads 320 miles, so 320 x .058 + 320 = 338.56 miles.
This seams right to me, but I'm no Mathametician. Can anyone enlighten me?
Thanks, JB

 

yep pretty sure you got it there. simply doing 1.058x320 will give you the same answer too.

 

Oh Yeah . . . duh! I knew it was a good idea to check with someone first.

Thanks, JB

 

Buy a Scangauge too. That'll let you adjust for larger tires so you have an accurate speedometer reading as well as distance with it's trip meters. I use mine to watch my speed around cops instead of trying to remember it's off 3.54957489 or whatever mph!