what type of performance problems would result from having one tire 205/60r16 91t and three tires 205/55r16 91h
It's more a safety issue than performance. You will have uneven tire wear, braking issues and the speedometer will be incorrect. Place it on the rear for now, But I would purchase a new tire to match the other 3. Or get a new set of 2 to match the others.
You will use more gas possibly mess up your alignment.
Tom's right only run the odd tire on the rear, if it is on the front you could mess up your spider gears in the front ring and pinion, then it will really cost you some bucks to fix it. Try to match up the tires as soon as possible just too be safe.
I do not think it will hurt its not taller or shorter its just a little skinnier, Put in the rear. Be aware of it and drive responsible, get the feel of it.
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