Planet-9 Porsche Forum banner

1 - 5 of 5 Posts

·
Registered
Joined
·
851 Posts
Discussion Starter #1
I was doing my first autocross in the Cayman yesterday, so I was keeping a close eye on the tire temperatures. I was very surprised to find there are vents in the front wheel wells which were blowing hot air on the front tires (I leave the engine running between runs). Examining the front end I see that there are two small radiator cores one in front of each wheel, rather than the conventional one larger central core. With a couple of fans to move air when the vehicle is stationary and the air exiting in front of the front wheels, you have tire warmers.

This is important for several reasons. I was worried my front tires were getting too hot, the Dunlop ZII I use for autocross like to operate around 100-120°F and I was seeing 140°F, where I start to worry about the tires needing cooling. The heating is not uniform, its blowing on the front of the tire, leaving the back colder. That was throwing off my measurements and sounds like a recipe for weird handling if the tire doesn't have uniform grip as it rotates. I took to moving the car a bit while waiting for my next run to even out the heating.

If we ever have a really cold autocross again (like we did last December), this could be really handy, I've found it difficult to get heat into the non driven wheels (its really bad in a FWD car where the rear tires do nothing much so never get any heat). There's a section in the SCCA rules (6.11) which specifically bans the "preheating" of tires "electrically heated covers or by similar means". I had wondered if a blanket which was warmed by sitting on top of the engine would be allowed. This is much more convenient and I don't think this contravenes that rule, its not heating the tires, its cooling the engine.
 

·
Registered
Joined
·
911 Posts
As I have been wondering why my front tires warm up much faster than the rears, thanks for your post.
 

·
Registered
Joined
·
1,301 Posts
. . . . the Dunlop ZII I use for autocross like to operate around 100-120°F and I was seeing 140°F, where I start to worry about the tires needing cooling. The heating is not uniform, . . . .
Where do you get this information for the tires "optimum" operating temperature? Is this something Dunlop published? Thanks.


Sent from my iPad using Tapatalk
 

·
Registered
Joined
·
851 Posts
Discussion Starter #4
Where do you get this information for the tires "optimum" operating temperature? Is this something Dunlop published? Thanks.
Its pretty much a guess from running them all this year.
 

·
Registered
Joined
·
166 Posts
my FP boxter had two big radiators with fans we could turn on and off maually to manage heat. Just happened that tires were warmed. LOL!
 
1 - 5 of 5 Posts
Top