I have 295/40/22 Pilot AS4 and one has a nail which is causing a slooow leak. At Discount tire they said to leave it as if they patch it will not hold up due to where it is. I asked to buy one tire but they said being AWD will not be even with all tires and one being brand new and will mess up. Is this true or are they just wanting me to get all 4? Anyone ever have this happen? The three other tires are at a 7 so may need to replace in the next 6 months or so.