Originally Posted by 40FiveSeventy
Before anyone throws things, I did a keyword search for my question, but didn't come up with anything conclusive. After my adventure of losing a tire, I'm going to obviously be putting new tires on my jeep. I'm looking at 31's that will fit on stock rims, so I don't have to do any spacing or lifting right off the bat. I also understand that upping the tire size means regearing AND changing the speedo gear to be accurate - but here's my question - does it matter which of those I do first? I figured it should go - Tires -> Regear -> Speedo gear, because how many teeth you need is dependent on the tire/gear ratio matrix, right? Just looking for some clarification. I don't want to do things wrong.
You got it !!
But will comment that you might not need to regear if you are happy with the performance. In fact I`d bet you with that small of a tire change you won`t need to.
Speedo gear. I`d use a GPS to see how much your speedo is off. Do not think it will be much. Yes, I am taking into account the ECM and VSS signal.
Put some fresh meats on it. Drive it for a week or two. Then make your decision(s).
Here is a chart you can play with
Just for kicks I plugged some numbers in
30 to 31 inch tires
Found a 3 mph difference at 2500 RPM with going from 30 to 31`s.