Spare Tire Question

[StarsnBars]

Morin all, Great spring day here in the midwest. I upgraded my tires to 35's except for the spare. Its a 33. Question,,, Will a smaller tire hurt my driveline if I get a flat ?? It would be short term till I could get the flat fixed. My service rep at the Hummer dealership said it wouldnt be a problem as long as I kept the speeds down and got the flat fixed ASAP.. Getting ready for our yearly fishing trip and trying to decide if I need to spring for a new 35 for my spare. Really dont want to spend the 200$ for a spare, but messing up my drive train fer sure isnt a option. So any helpful input would be nice. Thanks..