entropy
Moderator
Posts: 8671
|
posted April 24, 2009 11:44 PM
quote:
Tires can grow as much as 14mm at high speeds
gixx,
what specific tire are you referring to???
____________
This moderator uses moderation in moderation
  
|
Gixx1300R
Expert Class
Posts: 218
|
posted April 25, 2009 06:37 AM
Mostly all of them. I know that there are tires marketed as zero growth but that is a marketing ploy. At high speeds all tires expand.
|
tcchin
Zone Head
Posts: 867
|
posted April 25, 2009 07:32 AM
Not true. The older construction Dunlops grew 14mm at speed, but the Dunlop N-Tech's do not, and neither do the Pirellis. I have verified both the growth and lack of growth on the track and on the dyno. Sure, there's still a little deformation at speed in the new generation tires, but not like there was in the old Dunlops.
|
Shane661
Needs a life
Posts: 11494
|
posted April 25, 2009 08:51 AM
 Edited By: Shane661 on 25 Apr 2009 16:54
Regarding tire growth...
I am thinking that any additional tire diameter gained by growth might be equally or more offset by increased slip, due to a more crowned profile at speed. This is assuming you have enough hp to overcome the available traction.
Just thinking out loud here...but a 190/50 that grows at speed to the same height as a 190/55 will have less contact patch. Now, if that is all the traction you need, you might actually reap a small benefit from decreased rolling resistance.
After all, any more traction than you need is drag...
Shane
|
Gixx1300R
Expert Class
Posts: 218
|
posted April 25, 2009 02:05 PM
quote:
Not true. The older construction Dunlops grew 14mm at speed, but the Dunlop N-Tech's do not, and neither do the Pirellis. I have verified both the growth and lack of growth on the track and on the dyno. Sure, there's still a little deformation at speed in the new generation tires, but not like there was in the old Dunlops.
And at what speeds did you do your testing. I have been involved with tire testing at Daytona for the last ten years and I have seen a tire that did not expand after 160 mph.
|
tcchin
Zone Head
Posts: 867
|
posted April 25, 2009 02:33 PM
quote:
And at what speeds did you do your testing. I have been involved with tire testing at Daytona for the last ten years and I have seen a tire that did not expand after 160 mph.
Track speeds were in the 185 MPH range and dyno speeds were in the 195 MPH range (verifying top-speed limiter removal in 6th). We've used 17" KR108's (758's, 640's, 3136's, 3127's, 7127's, 7704's, 6680's) for many years and have experienced first-hand how the tires of various design generations behave with speed and temperature. I can verify that the N-Tech construction controls growth at speed very well compared with the non-N-Tech construction. We also tested Pirelli Diablo Superbike slicks several times and found that they do not grow significantly at speed either. The non-N-Tech Dunlops used to grow so much that a gearing change was required when switching between them and the N-Techs.
|
|
|
HOME
NEW TOPIC