Can anyone tell me what the back side offset is on my Rally II wheels on my 1969 Firebird. They are 14x6 factory wheels with drum brakes all around. I've heard from people with Firebirds that its ether 4 inches or 4 1/4inches but I don’t know for sure and I would like to find out. Reason being is I might switch out my drum brakes to discs in the front and I want to be sure it will work with factory wheels with no clearance issues.

As well can anyone decode the codes beside the valve stem for me? They read as follows MI-9 6 26 JM

Date looks to be June 26 1969. JM doesn't seem right. Here's a link to an identification page. They should be JO or JC. It does seem like those only fit drums but I can't be sure.

http://www.pontiacserver.com/wheels.html#rally2

Yeah the JM code threw me off a little as well as I've always thought the codes for 69 firebirds Rally II's were JO & JC or so I’ve been told. I've been on that site you mentioned before Jim but unfortunately it doesn’t mention anything about the code JM. I've always thought these were original wheels on my 69 bird but now I'm not that certain as I was contemplating selling them. But I really need to what the code JM is for. If anyone out there knows please let me know.

I'll find it. OK found it. JM is for 1970 Firebird and Grandprix excluding TA. I should be able to get you the backspace measurement later.

Hmmm this doesn’t make sense Jim because MI-9 = 1969 and the 6 as you said = the 6th month which is June and the 26 = the 26th day. How could these wheels be for a 1970 when the codes read MI-9 6 26 JM – which decoded mean a 1969 set of wheels.....lol....this is strange.

Not too strange. They were making wheels for the 70 models in June of 69. They may have run out and used these if your car is a late production.

Good point Jim that could be a possible scenario. I called a local firebird and camaro shop that specializes in old parts for these cars they told me that the JM = drum brakes.

I've heard both ways. It would be good to measure them.

Well from what I'm able to tell from the code so far isthat MI-9 6 26 JM - means this is a set of 14x6 Rally II's form June 1969 for drum brakes Firebirds.

A friend of mine has a set of JT coded 1967 original Firebird rallies that I think he would part with. These are the ones for discs and drums.