Help! We are currently travelling in Mexico and are unable to purchase an RV tire (ST). Today we purchased one truck tire LT, to become our spare, which is of slightly different size than our trailer's 4 running tires. Any opinions -- or better yet, good knowledge --- about driveability? control? danger? safety? damage? if or when we ever have to use the new "spare" as one of our running tires with 3 of the 'other' size?? Here's the data. Current tires (4): Load range D, ST235/ 80R16. Spare: Load Range E, LT235 / 85/R16. Thanks for any and all help.