Tires...what are you running?

[Tom Wells]

Argess,

Very nice, comprehensive look at rubber hardness.

Alas, after being involved in tire construction and testing for 7+ years, hardness is not the only factor in tire safety. I definitely agree it's one factor.

Another consideration, perhaps invisible from outside the tire - but not always - is internal adhesion between the various layers of rubber, and between the rubber and its reinforcing tire cord.

Occasionally there can appear a bit of a bulge, or surface irregularity that gives a clue, but often there's no change visible to the casual observer.

As you accurately point out in so many words, the chemical composition of a tire changes over time. You might say it ages. As it does, adhesion can be reduced between the components.

As aging occurs, and it often reaches significant effects around the 5 to 6 year mark, the tire becomes structurally weaker. The rate and the extent of the loss of strength is dependent on a myriad of factors such as its design, materials, original chemical composition, any trauma that may have happened over its life, temperature conditions, and probably ten or twenty other factors.

Agreed, these cars are usually lighter in relation to their tires rated load capacity so the effect of the weakening may take longer to appear. Conversely, speed, acceleration and braking forces may hasten failure, even on a lighter car.

So, as Clint once famously said "How lucky do you feel?"

I change mine every 6 years. Anything more than that is a big dice roll - maybe it adds to the thrill?

Tom

[MKS427]

Tire pressures are huge as these cars are light. My buddy has BFGs on his Cobra and he had traction issues. Somehow his pressures dropped to 14 psi front and 11 psi rear and he couldn't believe how much "better" his tires had been lately. Obviously, it is not recommended to run that low and when we upped the pressure the tires were slick again.
That said, these cars are light and the tires do not work well with 30-35 psi. I run Nitto NT01s on 17" wheels @ 22 psi per Factory Five's recommendation and they work considerably better at 22 vs 30. I do not know the recommend pressures for 15" wheels/26.5" tires, but I'm guessing somewhere below 30 psi.
I have been told, with the Nitto's, you want to be scuffing to the top of the triangles on the sidewall.
All that said, the best traction additive, I've found so far, is 200 lb plus passenger. ��

[BigGuy]

Had Goodyear Eagles but after 14 years (way over due) time to change out!
Avon’ s are pricy but my issue is they do not last long. (also not available in this area). I like the look of billboards.

So Goodrich T/A’s are on and 245 60 15" fr and 295 50 15" rear.
Talked to my tire guy and 5-6 years should be max for change out.... although
I don’t track. So I was WAY overdue! Not many choices that are DOT rated.
They are a little slick at 48 degrees yesterday, but a little driving and they will work fine.

[lnfletcher]

Originally Posted by Tom Wells

As aging occurs, and it often reaches significant effects around the 5 to 6 year mark, the tire becomes structurally weaker.

Tom

Taking this into account, I need to do more burnouts to wear them out faster!