The consensus seems to be they are not...
According to a recent study by J.D. Power, customers with run‐flat tires are less satisfied overall and replace tires more frequently in the first two years of ownership than do customers that didn’t buy run‐flat tires.
The report says the replacement rate for run‐flat tires is slightly higher in the first year of ownership with 10 percent of run-flat owners reporting a replacement versus seven percent with non-run flat tire owners. The difference becomes larger in the second year of ownership, where 27 percent of run‐flat tire owners replaced at least one tire, compared with 16 percent of non‐run‐flat tire owners.
“It’s vital that auto and tire manufacturers address the ride and wear issues, which are still not meeting customer expectations,” J.D. Power global automotive director Brent Gruber said. “Customers expect that run‐flat tires won’t compromise tread life or the ability to provide a quiet and comfortable ride.”