Girls, do you care if a man has a tight foreskin?!

I don't see why girls should care = really none of their business.
Many girls have FSD problems themselves.

Depends what is tight
Mostly at 15 it is because penis is growing
and foreskin will adjust by itself in a year or so.

Most guys this sorts out around 16.
Just be careful not to tear it by forcing it too soon.

He can roll condom down over the top of foreskin if he has sex.

+

A boy's foreskin should be able to be fully, freely and painlessly retracted from about the age of 8 and parents should teach their sons to do so daily to clean under it.

A teenager's foreskin which does not retract will be collecting a waste product called smegma under it. This will gradually decompose creating a nasty smell and forming a fine breeding ground for fungal, bacterial and viral infections which can very easily be passed on to female partners.

Since he is now 15 he should seek medical help, which is best given in the form of circumcision - a quick, simple and safe external operation which can easily be done under local anaesthetic in the doctor's office.

Circumcision totally cures/prevents phimosis, paraphimosis and frenulum breve. It reduces by up to 60% the risk of catching EACH of several STIs including HPV, heterosexually acquired HIV/AIDS and Chlamydia.

http://www.circinfo.net
http://www.circinfo.com

a foreskin can be stretched so it's not so tight anymore.

Wazir and Tyler have given helpful answers. I will just expand on those a little.
You can pass this on to your friend.
There is nothing wrong with him. He has a naturally tight foreskin. just like every other intact (not circumcised) man on the planet had at his age. Over 85% of the males on earth are intact so he is on the winning side. The other 15% wish they still were intact.
Follow the information in the links below and work the foreskin stretches into the daily shower routine. Let the warm water loosen and relax the skin before stretching. Stretches are to be firm, but gentle, with no pain. Pain is a damage indicator. Over stetching till it hurts can create micro tears in the skin opening that will heal over with non elastic scar tissue, making retraction more difficult. No pain,...ever!
Do not let him listen to anyone who says women prefer circumcised men. It is not true. If they care at all, it should be a preference for the normal, nature, healthy, as-you-were-born, intact man,....because circumcision is mutilation of the genitals. No child is born needing to be circumcised, and circumcision is never necessary.
If he does these stretches each day, he will begin to see good results in 2 weeks with full and painless retraction in 3-4 months. If it takes longer, it does. Just keep stretching.
What will happen is the Frenar Band (google it) of muscle that closes down the skin opening will relax and expand enough to allow the foreskin to glide effortlessly back and forth over the coronal ridge.
Go to: www.norm.org and read about the reason and function of the foreskin. He can see how very fortunate he is to still have his, and how misguided are those who promote circumcision.
Mithras

http://www.norm.org/
http://www.fathermag.com/health/boy-care…
http://sites.google.com/site/circresearc…
http://www.network54.com/Forum/244184/