Use of a logo that looks similar to a Professional Sport's Team's logo

What is the name of your state (only U.S. law)? PA

Is a charity event allowed to use part of a Professional Sports team's logo on our t-shirts we will be giving away for free?

Details:

Myself and others have organized a walk for charity. We have designed a t-shirt that we will be handing out for free to the participants. Within our design, we included three diamonds in a formation like the colored diamonds of the Pittsburgh Steelers logo on their helmets. Are there any legal issues with this? Since we are not using the logo itselt, which is made up of one blue diamond, one red diamond, one gold diamond, and the Steelers name next to it, are there any issues? Our three diamonds are all gold. Thank you so much for taking time to answer.

if there could be confusion, which apparently you believe there could be or you wouldn't be asking, you could have a problem with the use.

Why not ask the Steeler's office before you use it to determine if they have a problem with it because whether it actually is an improper use or not, whether or not the Steeler's would act upon the issue is a reason in itself to avoid the issue by changing your logo. If they want to throw their money and weight around, you would have to defend the suit whether you are in the right or wrong.

Very true statements, I think I'll try calling them Monday, should I call their Marketing number or their Administration number? Or a different number all together?

I honestly have no clue who to call and I suspect you will get tossed around trying to speak to anybody that will help you but I would try, none the less.

or, you could make a different logo that does not so easily remind you of the Pitt Stealers.