I have a 98 Civic. It came with a fake spare tire. I bought a used 14" rim and a used tire to use as the spare and threw away the fake spare.
It is now, sadly, time to retire the Honda after over 260,000 miles of near flawless performance. I bought a 2013 Kia Rio SX. It has 17" rims and NO spare tire - just a can of stuff to put in the tire and an electric air pump. The used spare tire I got for the Honda is less than 1" smaller in diameter compared to the Kia tire - much smaller difference than the fake Honda spare.
What problems are going to occur if I use my Honda spare as a spare for the Kia?