LT tires on TT

CapriRacer wrote:

Francesca Knowles wrote:

JJBIRISH wrote:

Actually in that situation I might use the P rated over a LT tire…

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No kidding- especially given that according to some studies, P-tires are three times safer than LT's- a little known factoid in some crowds.

Here quoting from this NTSB page:

NTSB wrote:
The rate of blowout-caused crashes for light trucks (0.99 percent) is more than three times the rate of those crashes for passenger cars (0.31 percent).

Blowouts cause a much higher proportion of rollover crashes (4.81) than non-rollover crashes (0.28), and more than three times the rate in light trucks (6.88 percent) than in passenger cars (1.87 percent).

Too bad P-tires are so flabby...but there might be some out there that would do the trick.

At first, I was going to challenge the statement about the differences in failure rates, but I see that it was attributed - and with a link! Thank you. But I did notice something that doesn't square with my experience in examining failed tires.

The report cited "blowouts" as a key difference between P type tires and LT type tires. Having spent quite a bit of time sorting through failed tires, there are 3 ways the term "blowout" is used:

1) A belt leaving belt separation - which isn't a true "blowout" in the sense that the tire loses inflation pressure as a first cause. In passenger car tires, a belt leaving belt type failure frequently leaves the tire inflated. In LT type tires, less so. But again, the first cause is the separation.

Yes, LT tires are more likely to fail from this than P type tires for 2 reasons:

a) P type tires aren't as intensively loaded - that is, hardly ever are cars loaded to their max - so the likelihood of failure is less.

b) P type tires were what the Ford/Firestone thing was all about (SUV's, too!), so it made sense to address those first. LT tires were addressed later - and this report is dated 2007 using data from 1995 to 1998, so they are using data that would be outdated even at the time they wrote the report. My best guess is that P type tires had gone through 2 iterations of changes by 2007, and LT tires would have gone through 1 iteration.

2) Another usage of the term "blowout" is a road hazard related loss of inflation pressure. LT tires are more likely to experience a puncture because they use higher inflation pressures, which makes the tire stiffer and less enveloping.

3) The last usage of the term "blowout" would refer to a non-road hazard related loss of inflation pressure - and that hardly ever happens. Other than belt leaving belt separations that result in loss of structural integrity, tires rarely have structural integrity issues.

So the report is using some information that will have changed between now and then - AND - I think the report is citing a statistic that is suspect.

Just one point, I don’t know and please correct me if I am wrong, the report is citing a statistic that would be suspect today, but when this all began in 2000 is when the data was solicited… there were 2 studies that were available at the time and both were used in the investigation to formulate the new rules the went into effect in 20007… these new rules were ready in a report in 2004… except for time for public input and time for final review and the passage of the final rule, plus allowed time for implementation brings it to 2007…

So at quick glance the data is suspect, but in context it’s not… it seems it was however the best available at the time…

To date though, I have seen no new data or independent reports… much of what I have read would itself be suspect and not independently done…

Certainly or hopefully some studies are being done on the effectiveness of the new rules and the safer built tires as well as the effeteness of the now mandated TMPS…

At first, I was going to challenge the statement about the differences in failure rates


It would seem by you opening comment that, you have some different and more current data…
Would you be willing to share…