I am trying to buy a Ford f250 however, my wife is unsupportive of the idea . Anyone have any valid arguing points?

The only valid arguing points would tend to support your wife's side of the argument. Very few people in this world need a F250 as their daily driver. More practical would be a small hatchback or crossover vehicle. If you can honestly come up with a valid use for the F250, then you need to stop and wonder...

1) How many days per year would the F250 be used when a smaller vehicle would not work?

2) If 1 is less than 30 days a year, wouldn't it be much cheaper to rent a truck on the days that the truck is needed?

Ironically, my wife wants me to buy a F250. I like Ford pickup trucks, too. But I honestly can't justify the purchase, just because my wife wants me to buy it. If I bought a new vehicle right now, it would be something like a ford escape, if they still make that...

So trade the beemer for a decent used F-150 with a back seat, and call it good. Not a diesel, just an F-150.

If you are asking for an excuse to buy a third vehicle when you are working security, there isn't one- but there is a good reason for ditching a beemer. Parts are expensive. Or you can wait until it's really in the budget.

Unless YOU can explain it, YOU don't have a prayer.

Are you a man?

I tell my GF what I am going to do, she knows now to accept it, because its not a question as its my life i do what i want when i want with my money. She dont want no truck, tell her she aint paying for it, and if she wants to be single, carry on telling you what to do. Soon shuts them up.

If you are a man, you don't need arguing points to buy a truck. A 250 is kind of a high school kids truck. You need to get at least a 350, preferably a Super Duty, or big Cummings powered Dodge, with 4 wd. Get a lift kit, bigger wider wheels with aggressive off road tires. It must have a roll bar with a bunch of halogens on it too. Don't settle for a wimps truck or a posers vehicle. Then you don't ask the wife, you TELL her!

There's no way to give you a helpful answer when you haven't told us why she objects. Is it too expensive? Does she feel you need a family car instead of a truck? Is she a die-hard Chevy fan? It's pretty hard to overcome someone's objections if you don't even know what those objections are.