another rims question

[Copperstang87]

I have a 87 mustang GT, with the stock 15x7 rims on there now, I purchased a set of 4- 15x8 eagle alloy rims with a 30mm offset and when I brought them to a tire shop to have the new rims installed they told me if i install them they will rub so they won't install them, I bought them used off a friend so I guess I have no choice but to sell them since they won't fit my car. I'm still confused what offset these rims could b in order for them to fit without rubbing.

I have P22560R15s in the front and P25560R15s in the bank

Thanks.

 

[87'GTstang]

I am curious too what the max offset rim that can be used is.

Keep in mind the other factor to not forget is backspacing which in my opinion is more important because that is the actual number that will make a rim mount too far inward. Backspacing is the amount of rim from the hub it mounts to to its edge and offset is how much off-center a rim is on a vertical axis and can be responsible for fender rub on spring compression.

Which brings me to a question of my own, anyone know the maximum amount of backspacing before the tires/rim starts interfering with suspension components?