Dumb trainer + tire choice

I have found a few discussions on this, but wanted to see if we could have a more comprehensive discussion, as I feel that there are more details that are being missed. Here is my question:

In December 2020, I started riding Zwift. Here is my setup:

  • Elite Qubo (gray roller) dumb trainer
  • Fuji road bike with Continental GP 5000 tires (started with road tire as it was pretty worn to start with).
  • I established an FTP of 200 through general riding as detected by Zwift through my first few rides as I was trying to see how I liked the platform.

As I rode more, I decided to subscribe and then discovered that “trainer tires” existed. Perfect, so I bought the Elite trainer tire (red one) and started riding. Immediately, I detected that the resistance had increased relative to the road tire, but I pushed on. My power numbers reflected this as my peak power had dropped 10-20%, however, over longer efforts, the power had only dropped marginally 2-5%. What concerned me was that I was no longer able to sustain 190-210 watts for more than 3-5 minutes. Specifically, the increased cadence drills were extremely difficult.

  • Did this mean that my 200 FTP was false?
  • Should I do a new FTP test with the trainer tire and is that more reflective of my true FTP?
  • Why am I concerned with FTP as I am a recreational cyclist and never going pro!?! ha!

Anyway, long story short, after ~500 miles on the trainer tire, doing the 6 week FTP builder plan, the tire developed a bulge and I needed to get a new one. While I sort out a warranty replacement, it was back to the Continental GP 5000 and as soon as I put it on, I immediately could feel a difference. After my first ride, I was able to sustain 220 watts for 20+ min and Zwift detected my FTP had gone up to 213!

So here are my questions:

  • On a dumb trainer, which tire is giving you a more accurate representation of real life conditions or resistance - the trainer tire or the road tire?
  • If the trainer tire does provide more resistance, does it make sense to do workouts with the trainer tire (adjusting FTP to account) and then for longer rides or races, use a regular road tire?
  • Note, I am a Cat D Zpower user, so I am not going for podiums and additionally I am not blowing away people with crazy speed to the point where I would get “coned” - I just want to be quasi competitive and not burning all my matches to overcome the trainer tire resistance load.

Finally, I realize that I could just solve all of this by dropping $1000 on a smart trainer, but to be honest, I would rather take the money and invest in a new, real bike as again, I am just a recreational cyclist. Thanks in advance for any thoughts!