I installed 225/75/R15's on my 03 Tracker 2.0L 4 Cyl. Good tires, but now it wont hold OD on the highway.

Its ridiculous the RPM difference from 3rd to OD. It goes from 4500 down to 3000 at 110 km/hr. Then it bogs at 3000 at the first gust of wind and kicks up to 4500.

Anyone know what the stock diff gears are for my tracker? Im hopin 4.62 so I can swap in some 5.12's, or any other suggestions?

Thanks,

-Steve