[DeTomaso] 265/50-15 tires

michael frazier red3644 at hotmail.com
Thu Jul 26 16:02:46 EDT 2012


I talked to a B F Goodrich tech years ago about the Euro T/As and specifically about the 305s we all use on the 10 inch Campys.
He talked about this extra ply on the Euro tires and that the 305s were even more resilient...in other words, great tires far exceeding specs.
He mentioned a mark on the side wall indicating this but I don't recall what it was and I don't have one in front of me to jog a week memory.
Wish those tires were still available for those running 10" Campys.
 
My problem is another tire availability issue....
I'm running 10" and 13" 10 spoke wheels on a flared car and will now use asphalt sprint car slicks grooved to whatever tread pattern i want.
The 345 Yokos and Pirellis are to short for a GT4 car.  The GT5 & 5S cars have a different flare profile and look OK with them. 
 
Michael

> Jack,
> 
> Just curious, what's the point of your message?  What are you trying to tell us?  I don't understand.
> 
> There is a HUGE difference between an 'S' rating and an 'H' rating. The following are a few excerpts from an interesting thread with info from a tire engineer for a major tire manufacturer:
> 
> All tire manufacturers utilize an "over-design / under-utilize" methodology.  It's been found that barely meeting the conditions - load 
> capability, speed capability, etc. - results in a certain rate of 
> failure in the real world.  And while we can talk about under inflation, 
> road hazards, etc., the reality is that over-specifying a tire results 
> in reduced failure rates.
> 
> Pretty much every tire will pass an S rating.  (Please note that I'm 
> limiting the discussion to regular passenger car tires.  Winter tires 
> and light truck tires are a different story - similar, but 
> different.)  And T ratings are not much of a stretch.
> 
> So an S rating would - on the surface - seem to be adequate for use in the US where there are speed limits everywhere.
> 
> But,
> in order to pass an H speed rating, a tire more or less has to have a 
> cap ply.  This change has a profound effect on failure rates, way beyond
> what the increase in speed rating suggests.  The failures rates are so 
> low for tires with cap plies that court room "experts" claim that tire 
> manufacturers are negligent for not using cap plies even in their S 
> rated products.  (My response to that is that these "experts" must also 
> be saying that tires ought to have a minimum of an H speed rating - and 
> if that is true, the "experts" ought to be lobbying NHTSA to specify H 
> rated tires for any tire sold in the US.)
> 
> But the point I want to
> make is that the step between T and H is enormous from a tire 
> durability point of view.  And I don't recommend anyone use anything 
> less than an H rated tire.  Considering that the risk of a tire failure 
> includes fatality, the cost / benefit seems to be there.
> 
> 
> A cap ply is an additional layer of a fabric and rubber composite that is applied over the belts and oriented in more or less the circumferential direction.  What it does is restrict the growth of the tire in the 
> circumferential direction - like centrifugal forces.  But I also think 
> it adds bulk and reduces the standing wave, which may actually be more 
> important in the context of tire failure.
> Source: http://www.eng-tips.com/viewthread.cfm?qid=159900
> 
> Additional info:
> http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CGcQFjAB&url=http%3A%2F%2Fwww.nhtsa.gov%2FDOT%2FNHTSA%2FVehicle%2520Safety%2FTest%2520Procedures%2FAssociated%2520Files%2FTP-139-02.pdf&ei=5IkRULfdCcfhrAfQjYGAAw&usg=AFQjCNEYEuipPu_2ACn67-1IsQDHUhGMHw&sig2=2c9ZNOZl-06muDXE-nk4vQ
> 
> 
> 
> --- Original Message ---
> "S" speed rating = 112 mph max sustained (30 min. test)
> "H" speed rating = 130 mph max sustained (30 min test) That may mean that's all the mfgr decided to ask they be tested to, or.... FWIW- J DeRyke
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