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I think if the climate is hot enough where the tires heat quickly, you could drop the cold tire pressure to make the car ride better.
I have two other cars with the same tires and GM recommends 35 psi on one and 33psi on the other, I think because it is a trade off between gas mileage and ride.
My Camaro pressures are recommended for 35 psi, but I have dropped them to 33, especially during 100 degree weather. Otherwise, they end up at 37 or 38 psi.
It does make sense to adjust the cold pressures so that the final pressures stabilize where you want them...an extreme example would be starting with lower pressures on a racetrack because under cornering loads AND temperatures they will heat up even more than on the street.
i think if the climate is hot enough where the tires heat quickly, you could drop the cold tire pressure to make the car ride better.
I have two other cars with the same tires and gm recommends 35 psi on one and 33psi on the other, i think because it is a trade off between gas mileage and ride.
My camaro pressures are recommended for 35 psi, but i have dropped them to 33, especially during 100 degree weather. Otherwise, they end up at 37 or 38 psi.
It does make sense to adjust the cold pressures so that the final pressures stabilize where you want them...an extreme example would be starting with lower pressures on a racetrack because under cornering loads and temperatures they will heat up even more than on the street.
Our low temps here in Palm Springs, CA are now in the mid 80's where I have (cold start) pressure @80~85F set to 30psi....
However, buy mid afternoon when it hits 115~118F this time of year my tires will read 34~35psi....But I'm ok with that as the ride is still relatively smooth and handling is well behaved...This is with the stock run flats (which I don't find all that harsh) and I also don't have mag ride...
30psi cold (as in overnight cold, check first thing in the morning) is the factory spec.
What tires do you have? Do you have any suspension mods at all?
If you're looking for a really smooth ride, you have the wrong car. I hate to be that blunt, but there's only so much you can do.
Minor improvements can be made in ride quality. Lowering the cold tire pressures by a few psi can help, especially if you are traveling alone (no passenger) without any cargo/luggage. Start dropping maybe one psi at a time, and monitor how much the pressure increase when hot (highway speed driving especially). Don't go beyond the point where the hot pressure doesn't drop at all when you let one psi out cold. If you go too far, the hot pressure will actually rise, and you're in the "danger zone" then, with pressures too low. You also probably won't want to go below (or even near) the threshold where the TPMS light comes on because you get into bigger issues that flow from that.
Switching to a different tire can help. Run flats are particularly harsh. If you can live without the run flats, you can find more comfortable riding tires. I rode in one C6 on Continentals (not run flats) that seemed to have a very good quality to the ride. Less bumpy and less road noise. Others might have some recommendations here for a C7.
I would caution on reducing tire pressure below what's recommended. Just remember the Ford Explorer/Firestone tire control issues at speed. Sure, your Corvette won't rollover (probably) but you may lose control when you need it most such as when you're on the highway and have to evade a driver or object. That's when you need max control, max performance, max predictability. Going in to "guesswork-land" with an unknown pressure is for tire company testers and race drivers on the track (notice how team managers adjust tire pressures for better grip or different handling).
Your car, every car will either increase or decrease tire temp, which has a direct effect on tire pressure, depending on ambient air temp rising, or causing the tire to heat up or cool down. You can change tires for a softer ride, but there you're relying on some company's opinion which is hopefully true and accurate. It could be an expensive experiment. It may or may not affect handling, tire life, noise, etc.
I also know what "track pressure" is. Being on a track is a controlled course of organized chaos, not the streets and highways. Good on you to draw a parallel between the two!
The Exploder issues were when people either had slow leaks that they didn't know about, or they seriously neglected their tires and never checked the air pressure. Most were when the tire was under 20psi cold, and the blowouts occurred when the hot pressure significantly exceeded the maximum pressure shown on the sidewall.
Any pressure that someone uses for 20-30 minute track sessions is probably "safe enough" on the street. I've run down to 23 or 24 psi cold on autocross courses, but I've only been forced to run that out onto public streets and highways once. My friend/helper left early and took the air compressor with him, leaving me underinflated for the trip home. I stayed under 55 (mostly 35-45mph) to the nearest gas station with air available, which was about 5 miles away. I saw hot tires and 40 to 44psi tire pressures on that trip, and I parked it and ate at the Chinese restaurant before adding 8 psi at the air pump (bringing them up to 40-42psi again). After that, driving the C6 to its owner's home, the pressures actually dropped back to normal "hot" pressures of 34-35 psi.
If you're paying attention, it's certainly possible to drive safely below the factory specified "cold" tire pressures. There's at least a 10% to 20% "margin of safety" in those recommendations. The key is, if you do it, 1) You're at your own risk, and 2) you need to pay attention to tire pressures. With the DIC able to read tire pressures in real time, #2 isn't really a big issue, you just have to pay attention.
We can agree to disagree C6 Racer because this forum probably has some of the most careful, knowledgeable and DIY'ers for Corvettes (and their other vehicles) of all Corvette drivers. And yet....and yet, you can get an OP, and literally dozens of others asking this question about their tires, tire pressure, etc. week after week.
So, when you say, "If you're paying attention, it's certainly possible to drive safely below the factory specified "cold" tire pressures" And, when you say, "...The key is, if you do it, you need to pay attention to tire pressures." and, "...you just have to pay attention." I hope you are not assuming too much, even for CF members.
And btw, the Explorer/Firestone issues were not all about slow leaks and below 20lbs. pressure tires. You may not have seen it but several years ago a tire engineer was interviewed and in answer to looking at a car, which would he rather have: one that had either overinflated or underinflated tires? His answer was that in every case, he would much rather see a car with a couple pounds OVER the recommended number than even one or two below. When asked why, he said, "Because I know that most people hardly ever look at their tire pressures, and I'd much rather they have that cushion of a couple more pounds than seeing that the tire is already down, and likely to go lower, dangerously lower."
Do you disagree? Remember: we're not talking track times, or autocross where after each run, you adjust your pressures, do cool downs, etc. This is the real world where nothing is predictable on the roads and highways, and few people check their pressures--ever.
In the CA central valley, I have found that 30 psi cold allows the tires to consistently warm up to 35 psi regardless of air temperatures, which routinely reach 100+ in the summer.
On the track you can actually check tire temperatures across the face of the tire to see if the pressures are right so that the tread stays in contact with the track under various conditions..
I actually run a pound or so less cold pressure in the front so that when the fronts pick up the extra heat from brakes, engine, cornering,etc., the pressures all equalize.
Track pressure is 26 cold, better traction, worse wear. Lowering the tire pressure a bit won't make you dick fall off.
That is only as the tires get much hotter when Tracking and pressure increases! Suggest the OP get the MRC software update as it does eliminate the initial harshness when you hit a bump and keep the 30 psi.
With the recent heat wave of 8-9 days in a row near 100º, my tires starting at 30 psi, hit 32 psi in about 5 miles, 34-35 psi within 30 miles, and the ride is noticeably harsher even with the newer MSRC calibrations. That's just in conservative street driving. I'm going to dial mine back to 28 psi for the remainder of the summer.
Mine are set at 28. Rides good and haven’t noticed any tire wear. If you can notice a couple pounds different of tire pressure making a big ride change, then my compliments to you. Maybe on a track but not on our crappy roads.
07-06-2018, 06:38 PM
Tire Pressure
