Hi! I registered here about a year ago when I was buying my first road bike but haven't posted anything before now.

I have a 2019 Specialized Tarmac SL6 Disc Sport and love it. I recently decided to upgrade my wheels for races and bought a set of Shimano WH-RS770 Ultegra wheels. They haven't been delivered yet.

I also purchased some Conti GP5000 TL 28mm tires. Here is where I think I messed up. I figured because the roads here in Hawaii are awful and I'm reasonably heavy (200lb) I could use the extra cushion on a high-speed descent. But with my relative inexperience I hadn't thought about frame clearance, aero (I'm probably not a fast enough rider to really need aero, but it's still a factor), etc.

The tires arrived before the wheels and I can return them for some 25s. I'd really rather not open the package at $70/tire and then find out they are useless.

I know "tire width" questions are about as welcome as a political debate, but I could really use some experienced insight. Will these tires fit on my bike at all with this wheelset? If so, ho bad is the profile going to be and will that be a detriment in an olympic triathlon? I'll never do an ironman or even a century ride most likely, but I did buy this bike and tire set to do as much damage as I can and would like to make it count.

Thanks to all for helping. Also, I tried to find where to post this and chose as best I can. No hurt feelings if a moderator needs to move it.

Edit: it may help to know that the stock rims are 20mm internal, but the Shimano wheels are 17mm internal. I know that makes a difference but not sure how. Also, I've read that Specialized says that the Tarmac has 30mm clearance based on actual inflated tire dimensions.