IcemanG17

here are some pictures of the widows rear tires after two full DE days.....granted I'm no tire expert but it looks to me like i need to bring the tire pressures down to make the contact patch wider???? currently set at 37psi hot with a temp variance of 10 degrees hotter on the inside

mark kibort

looks like you are running a 285 effectively.

what are the temps you saw the 10 degree spread. that 37psi at 120f is another animimal when the tire is 180F.

Start at 28psi cold, or ambient and you should be absolutely fine.

mk

IcemanG17

MK
The rears were 140F on the inside and 130F on the outside....the fronts were the same but higher in the mid 140s to 150's

I am starting at 28psi cold...but that quickly became 42 hot!!! which we were dropping down to 38 front 37 rear after every session....

mark kibort

A lot is different with the squirmy full tread. full tread can give some weird temps. Kind of all bets are off. but, you are probably fine. run them for the year, see the wear patterns, and maybe at half life, you shave them down.

mk

M758

you can run them lower or with alot less camber. You should be able to run them so that the wear stops at end of rain groove on the outside edge of the tire.

Interesting because on a 944 spec car usein 225/50 R15 at 40 psi hot we get much more side roll over. Even with -3.5 and -2.5 camber.

todinlaw

It looks to me like you have to much negative camber. You will never increase the contact area with air pressure, maybe changing the rim size, but if you want more outer edge reduce the camber on the left(drivers) rear. I have found the larger the rim size and tire width the less camber is needed, I am talking about small changes hear not 1 degree difference.

mark kibort

the 335 is a monster tire. at 2 degrees I was rubbing off the outside edge, just hitting the arrows. (one check point) however, i was still leaving a lot of inside edge tread untouched, gathering up a lot of track rubber. the 335 is probably too much tire for this car which is pretty light in the rear. the 315 is more ideal or the 305 even better with the slightly taller side wall. You also have a few other things working against you . your very light spring setting in the rear, creates even more camber which can artificially change camber during hard turns. once you get the cage in and some stiffer rear springs, you will be just fine.

mk

IcemanG17

The adjustable sway bar is in now too and set to the middle setting.....the rear camber was 2.1' which will be adjusted down....maybe 1.5? Or even 1.0?

mark kibort

1.5 wouldnt hurt, unless you are plannng to get the stiffer springs soon. Im actally at 1.8, and cant get any more out of mine.

mk

Dennis K

That 10° difference inside to outside is exactly what the books & tire engineers say is ideal. 130°-140° is low though. As you start pushing harder, you'll probably start using more of that outside shoulder.

28 psi cold to 42 psi hot is a bigger jump than I've ever seen. I usually gain 7 to 9 psi going from cold to hot. Maybe there's some water in there?

IcemanG17

I've been researching this and found the same info...since I am not pushing the tires 100% once I reach that level it should even out the temps....so I think I will leave it alone for now....

I will keep a closer eye on the cold vs hot pressures next time.....

mark kibort

Yeah, 28 to 42 is doubtful. I would like to actually see that one! I think Brian said he is ending up around 37-38psi and that is about right. the full tread tire can give some funny readings too, both in tire temps and pressure. 10degreeF accross the tire is what i generally see in all conditions except rain! If you are working the tires well, 180-200F in the hot pits. 170ish if you have a slightly slower cool down lap and a 1 -2 min cruise to your pit stall.
mk