In May 2022, my Ford dealer told me I needed to replace my tires in order to meet inspection. Since the original tires aren't around anymore, they suggested Eagle F1's as a replacement. These have a smaller sidewall than the original tires, but they thought they would work.
After they put on the new tires, I drove the car home. When I hit 70mph, the engine lost power and sounded awful. I was able to limp the remaining 2 miles to work at 45 mph. Once in the parking lot, I parked the car, turned it off and inspected it. I didn't see anything obvious, so I tried to restart it. When I turned the key, the power came on, but when I pushed the button, nothing happened. About an hour later, I came back out to the parking lot and restarted it without a problem. I was able to repeat this behavior - every time I hit 70, the engine goes into limp mode and won't go above 45.
My car has been at the dealership for months now. They say the problem is due to the smaller circumference tires. They say the computer is miscalculating speed and thinks the car is out of control, so it switches to a lower-power mode for safety. They have tried to reprogram the computer to recognize the new circumference, but the problem still exists. They said the new tire size is outside the original tire size parameters and they downloaded a custom set of values to tell the car the actual size of the tires. Long story short, after months of frustration, the car is still unusable.
I see that many of you have suggested Bridgestone tires as replacement for the original tires. I'm not sure why the dealer didn't go with the Bridgestones. They say they are dimensionally identical to the ones they put on my car. The dealer has basically given up on fixing the car and I'm not sure what to do next.
Any suggestions would be helpful.
Thanks.