Guys, my door stamp, gas tank cover flap and owners booklet states that my stock size tire on a 2002 XLT, extended cab, 4 liter OHC, auto transmssion is 225-70R-15 .
I tried to cut and paste a table from 1010tires.com but I can't carry the table forward, just a bunch of disjointed information. So, in the interest of clarity here is the information for you to review.

tire size section width Diameter Diameter Diff. % Speedometer error
225-70-15 8.85" 27.4" --- ---
235-70-15 9.25 27.95" +1.97% 2.015% too slow
235-75-15 9.25 28.87" +5.1% 5.372% too slow

So depending on whether you jump from my stock size of 225-70's or from your stock size of 235-70's will determin if you find a substantial difference in performance/speedo error, braking, etc. or just a little bit. I found the difference in the 225-70 vs the 235-75to be substatial enough that I went back to the 225-70 and I'm happy that I did. BUT, that's me and my psychy. Yours is probably different. If you like it (and it does look better), more power to ya.