Ok, so I recently bought tires for my 18" rims. I bought a set of Dunlop Direzza DZ101s from TireRack (http://www.tirerack.com/tires/tires....odClar=Premium). I got the tires mounted at a PepBoys near where I live.
I've recently been having troubles with vibrations on the highway, so I took the tires to a different shop (Discount Tire Direct) and had them check the rims, tires, and balance. Turns out it was a horrible balance job... Drove the car the same night on the highway, no issues.
Last night I drove downtown, on the same highway I tested the car on earlier in the week and was getting some terrible vibrations in the steering wheel. So I took the wheels back to the same shop (Discount Tire Direct) to check the balance again. The manager tells me that the tires I bought aren't for my car, she said that load index is too low for the car (These tires have a load index of 91). Apparently the stock tire load index is 94. She's telling me that the sides could crack and I could possibly have a blowout.
I called TireRack to see why tires with a load index of 91 were showing up in the search results for my exact car, but the guy I talked on the phone with said that 91s should be enough for my car.
TireRack is willing to send me 2 new tires to try to fix the vibration issue and Discount Tire said they'll talk with Dunlop to send all 4 back so that I can buy 4 tires with the correct load index (I would just pay the difference between the old set and new set of tires). I don't know what to do and who is correct!
TL;DR I bought tires with a 91 load index (which TireRack says is okay) but Discount Tire Direct is saying that those are too low and therefore unsafe to drive on. Should I stick with the 91 load index tires or exchange them via Dunlop for 94+ load index tires through Discount Tire Direct?