Is there such thing as pre-stretching the tires?

I have a set of Michelin Pro Race that are extremely tight to put on even after 1500 miles on it.

Any DIY tips on how to make the mounting job less agonizing?

Thanks in advance.

Never heard of prestretching. Let the darn things set outside in the warm sunshine for a bit, and the job will go easier. Well, maybe that isn't the hot tip in winter, but it does help.

Some tires just don't go on easy, or a specific tire has issues going on a specific rim. You will need a good set of tire levers and a bottle of soap and water. Spray the soap and ater on the tire/rim. This will make it slippery and you should be able to use the tire levers to pry it on.

Tires don't "stretch". Wire bead or kevlar.

Maybe just psychological, but it "seems" like some of the tougher wire bead tires I've got easier after mounting / un-mounting a few times.

They all have inherent give to them that many people would call stretch, and tubular tires do stretch.

I remember reading a post a while ago that said put your tire in the dryer to warm it up. It would be slightly larger, not much, but maybe enough to make a difference.

I've had two or three sets of tires that were all but impossible to mount, including a pair of Vittorias that broke FIVE plastic levers (I eventually went to the grocery store bike aisle for a set of those old, cheap steel ones). I had a flat on the first ride and couldn't get them off to fix it, the only time in 30+ years of cycling that I've had to call for a ride home. I finally cut them off the rims and threw them away. This seems to be a fairly recent development, and I'm inclined blame fear of liability--the tire companies would be at risk if a tire came off the rim, even if it were underinflated or improperly installed, so they make them just a hair tight to reduce that possibility.
End of rant. As for stretching, it's standard with tubular tires, but I've never noticed that it makes a difference with clinchers. Both wire and Kevlar beads are pretty tough...on the other hand, a tire is about seven feet in diameter, and even a millimeter of stretch would make mounting easier, so maybe I haven't been paying attention.

Is it just possible that these tires just got past quality control at the factory? Or perhaps like the odd sized 26" Schwinn tires, they were made for a special application?

What the hell do you ride that has tires that are 7 feet in diameter?

Perhaps circumference?

Maybe that's the danger of pre-stretching them too much?

I think one reply to that one was that don't try that trick if it's a kevlar belted tire. Some speculation that kevlar would shrink, not stretch, with heat.

My secret is to find a friend who knows the secret, and let him put the damn tire on.

only tubulars need to be stretched, inflated and seasoned
if the rider believes they are more supple (they are)

beaded tires can benefit from being mounted then run on a drum overnight with
an electric motor to add suppleness.

a racer usually does better when the tires have brand new tread but the sidewalls have
been worked or flexed as though it has been used for a few hundred miles.

this is the .00001% advantage. in other words, it is fine if you don't it is fine if you do. YMMV

It may not necessarily be the tire, but the Combination of Rim and Tire. I have a set of Campagnolo Proton's and have had a GREAT Deal of difficulty with Continental GP3000's and GP4000's. It could be the way Continental does their tolerancing, how Campagnolo does their tolerancing, the shape of the wheel cross section, a wheel at the high side of its tolerance range and a tire at the low side or all of the above...

Have a pair of Tandem rims that are very tight. To make it worse- I use Velox tape aswell.The way I get the tyres on is that as I work the tyre on by hand- I push the tyre well down in the well of the rim. When it gets to lever time- I put pressure on the lever and once again push the tyre bead into the well. Then lever tyre over the rim. Next levering and I do it again- Pressure on and push the bead into the well. Works every time but getting the tyre off is release the tyre from the sidewall and into the well all the way down and start praying.