What are u worried that could happen, spontaneously burst into flames? Carry a fire extinguisher.. Problem solved?

Totally fine to mix tires.

You are fine if the lower RR is in the rear. The bike will only slightly compress.

However, if it is in the front, you are screwed. The difference in rolling resistance will cause your bike to split in half with the front taking off and leaving the rear behind.

No really, it is not a big deal.

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Suffer Well.

I thought I'd be fine although I've never mixed and matched tires. The tread is very different on them, so I wasn't totally sure if it could cause an imbalance.

Have you heard about the time when Sergio mixed a tubular with a clincher?

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Suffer Well.

I use this exact combination. The shop only had one Corsa speed 2 left so I stuck that on the front and put a GP5000 on the back.

I am pretty sure that your bike is going to collapse into two pieces.

Sweet! I'm in good company!!! Probably was an availability issue at my shop as well.

Hopefully at the end of my race once I'm off it. Lol!

As others have said, no issues (other than bike snob fashion) with mixing tires.

Here's an example of it being done at the World Tour level at the Dauphine.


Here's Baekkegaard doing it at Kona 2019 on his way to finishing 15th:

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

This is exactly what I use on purpose. Good choice, even if by accident.

Just be careful GP5000 has a lower CRR and therefore has a tendency to try and overtake the front due to the greater CRR of the Corsa and can be quite dangerous when that happens...

I would say you have them the wrong way around.
If the aim is speed, I'd put the GP5000 on the front where the load may be slightly less, thus less impact from higher rolling resistance, but perhaps more importantly, the GP5000 is I think more aerodynamically advantageous than the Corsa.
Also since the GP5000 is a more robust tyre, and the front is the more dangerous place to suffer a sudden puncture, there's another reason to favour the front for the GP5000.
I can't see any reason to put it on the back except if you think the chances of a puncture on the back are greater do to slightly higher loading, which is feasible.

But of course the potential for tyre imbalance to split the bike in half does make these all mute points!

You make a good arguement, however having managed to get a Cosra Speed TLR and a latex tube on to my front wheel it is staying there until it needs to come off! Increased wear and increased puncture risk swayed my decision at the time, however the primary issue was how difficult it had been to get the Corsa Speed! If I had the choice at the time I'd have Corsa Speeds on both wheels.

I only TT, I don't do triathlons, and earlier this year - on the set up above - I rode a 22:05 ten mile TT, my PB is 22:04 - if I had put a Corsa Speed on the back instead of GP5000 I would have a new PB.