Spare Tire

I have recently replaced all 4 tires that came on my 37ft 5er. Original tires were ST235-80-16, with max pressure of 80 psi. I purchased Sailun LT 235-80-16, with a max pressure of 110. I retained the original spare (like new, psi of 80) to continue using as a spare. In addition to higher pressure and heavier duty, the Sailun tires are 1" larger in diameter. Will I have a problem in temporarily using the "smaller and lower pressure" spare tire if I have a flat or blowout. If problematic, I would need to purchase both an additional tire and high pressure rim. Thanks for your input.