Help Diagnose My Problem

[chico297]

I drive a 1991 Explorer sport for my winter vehicle. Absolutely bone stock. Couple months ago I went from the stock 28" tires to 31" tires. After putting these bigger tires on it drives fine in 2wd but switch it over to 4x4 and i get terrible clunking from the front tires during hard acceleration, turning and hard braking. The 4x4 was fine with the 28" tires. I'm thinking its the U-Joints, second opinion please?
Thanks

 

[Tony H]

What happens if you throw the 28's back on?
Just wondering if it's coincidence or not.
While the tires are off, grab the spline on the outer axle and see if there is play at the 'u' joint as you rotate it clockwise then counterclockwise.
I can't imagine why the bigger tires would make bad 'U' joints more pronounced.