Question: I recently upgraded to the C7 Z06 18/19 wheels and the Hankook 265/305. I started running them at 35 psi but it was a little too soft. Things got a little sloppy in the turns and overall just felt a little soft.

I then tested 38 psi yesterday which felt very good. Great combination of overall ride and handling. Took the wife on a nice long ride out in the boonedocks and eventually started getting these High Tire Press warnings for all corners. Every time you have to hit reset go get rid of the warnings but it just comes back in a few minutes. All the tpms were reading 42 hot, and I've searched and found that by default, this is normal.

So the question is, is there any way to remove just the high tire press functionality or up the threshold to say 45 psi. Dealing with the constant warnings is a pita. I'd hate to have no choice but to drop the pressures back down and suffer with the sloppiness just to avoid the warnings.

 

Wow !!! I run my Super Sports at 30 cold and have no issues, also running 18/19 's I also have Selective ride Control and run in the middle setting ???

 

 

There is no way that sort of tire pressure is good for those tires, sounds like a different alignment is in order. Any more than 35#, especially on the rears will cause the tire to U out. Causing premature wear.

There are lots of things that can contribute to "sloppiness". What wheels did you have on the car before?

 

Don't have any suspension problems but the Hankooks seem to have very soft sidewalls. At 35 psi the thing rides like my caddy. The old F1 runflats obviously were the opposite and I couldn't run those over 30 psi or I'd lose teeth. I did the chalk test today and at 38 psi the pattern was even across the tread, front and rear. I guess if I can't change the acceptable range, even with a Tech II, I'll have to try dropping a few 10ths at a time until I can consistently stay under 42 hot. Bummer.

 

I'm running Hankook Ventus V12s on my car at 30 psi cold and they ride and handle just fine. I'd search for something else besides the tire pressure as the cause of your concern.

 

How about going to get them filled with nitrogen so the tire pressure doesn't rise as much?

 

NO WAY that can be a good pressure! C5 respond well to running 30-32 PSI.. I have CCW 505a rims at 11.5 inches wide with 19" low profile tires and I run 28-29 COLD in the rears and 30 Cold in the fronts for optimal tire wear and performance.

Have the car properly aligned and see if that helps.

Drive the car over a small WET PATCH and then on to a dry road, and see what the over all tire foot print looks like. It will give you an idea on how much tire is in contact with the road. If just the middle is wet,, that's not good!

You can also paint a white stripe across the tread and take the car for a short drive. See where the majority of the tire wear is happening. I think you will be surprised on how much contact you DONT have at those pressures!

If you do some sharp turns at a moderate speed, that will show you how far you are running on the outside parts of the tread.

On motorcycles, we refer to that part of the tire as CHICKEN STRIPS!

Bill

 

Guys, I really appreciate the troubleshooting tips, but again there is nothing wrong with the suspension, alignment, etc. I was just asking about the ability to mod the electronics.

Again, I just went from the stock RF F1's, and at 30 psi the ride was bone-jarring. It is a stock F45 suspension with metal end links. The shocks have about 10K on them, so suspension wise, it's perfectly fine. Yes, the base suspension is soft, and I totally understand that. I will be upgrading the sways at some point in the near future, and likely the shocks further down the road when the F45 begin to fail, but that has nothing to do with dialing in the optimal tire pressure.

As mentioned earlier, I have done the chalk test at a few different psi's starting at 30, and at 30, the pattern was clearly fainter in the center of the tread. At 35 psi, it was pretty consistent across the tread which remained so at 38 psi, which I agree was higher than I thought I'd want to be. I am doing this on a long stretch of seal coated driveway so it's very easy to see. Also noteworthy, is that I'm dealing with Cold Temps around 78-80 degrees, so the equal psi at 70 degrees might be a psi or so lower. Lastly, I am using an extremely accurate air pressure calibrating meter we use for calibrating delicate medical equipment. So, if you are using the common air pressure sticks, do know they can be off as much as 2 psi or more.

Now, please keep in mind that the OEM 30 psi recommendation is based on running the stiffer walled RF's, and whenever making marked tire type changes, especially from RF to Non RF, it's always a good idea to retest tread patterns at different pressures, which is what I'm doing. Again, I'm trying to figure out the capability of modding the electronics if need be, and it seems the answer is no. Thanks guys.

 

Well,,,,,,,,,,,,,, To answer your exact question, the Tire Sensor LOW & HIGH limits are OEM programmed into the BCM and are not changeable.

The TPS Function can be programmed IN or OUT of a 2001-2004 C5

For the 97-2000 C5, it is not programmable at all. You can NOT access it at all in early C5s.

BC

 

Thank you Bill. Incidentally, I failed to mention that the OroTek II's they installed are reading high from 1 to just under 2 psi, and are variable amongst themselves, further exasperating the issue. It's 90+ today here in Chicago today and just did a quick lunch run. Dropped them to 37 psi cold and was bumping 42 psi on the DIC within 20 miles. When it's all said and done, I have a feeling I will have to run at an actual 35-36 psi cold, fwiw. Thanks again guys.