Best pressure for Cooper Pizza Cutter?

I just got a new set of 235/85R16 Cooper ST Maxx for my DCSB.

With the recent snow, ice, and slush here in Michigan, I'm really disappointed in how easily they are breaking loose as compared to my previous Hankook AT'Ms

I have 'em set at 45 psi right now. Anyone happen to know if I'm in the ballpark on air pressure? I would run a chalk test, but it's kinda hard with all the wet roads right.

Thank you

 

Seems high. I run Toyo skinnies, but 32 front and 34 rear.

 

Ya definitely a lil high I'm on 33s and I run them at 35-37 psi

 

Okay. I'll drop 'er down.

Thank you

 

New tires will also suck for the first maybe hundred miles or so (maybe less) - they usually have a coating on them that protects the rubber when in storage, and it will take a little bit of driving for that to wear off.

Lower psi should help as well.

 

2nd and 3rd gen; 43 psi

 

255/80/17 running 37 psi

 

6 months later, but hey, zombie threads are fun .

I did the chalk test with my 235's. It suggested 30 psi. I then looked at the load rating and decided I didn't want to routinely run them that low so I'm doing 35 in the front and 30 in the back.

Edit clarification: I mean I didn't want to run them at the chalk-test value of 30 psi due to load ratings.

 

My $.02: This is a good example of how the chalk test isn't everything. The reason pickup trucks typically have a higher recommended PSI in the back rather than the front is not just because they expect owners to actually haul stuff in the back, but also because having higher tire pressure in the back promotes understeer rather than oversteer and keeps the handling from getting squirrelly, especially in slick conditions when the bed is empty. Mine says 26front/29rear, but I keep it at 35/38 to maintain the same ratio. Yes, of course the tires are going to wear a bit differently front/rear, but that's because the tires on each respective axle have different tasks. The solution to uneven wear is to just rotate them religiously every 5K.

If you email Cooper, I'm sure they'll be able to recommend a PSI based on their load/inflation charts. My guess is it's going to be higher than you're hoping for.

 

And did you have a scientific reason for that, or just the 'didn't want to'?

I'm not understanding the value of more pressure than required?

You're getting more center tread wear and less contact patch.

Well, you've kept the 3# delta, not the same ratio.

Years of SCCA time gives me reason to disagree with the 'chalk test fail' concept on a street vehicle.

But I do agree with your frequent rotation recommendation. Not because of wear differences from pressure deltas, but because of cornering and braking wear on the fronts.

I always suggest a chalk test proven pressures for everyday driving (whatever that is) and if you load significantly (like for a trip) another test and the resulting pressures from that for those particular load conditions.

 

Yea, sorry, I wasn't very clear. I didn't want to run the pressure indicated by the chalk test because it lowered the tire's load capacity too close to the actual weight of the empty vehicle. The OEM P-metric tires at 30 psi, would carry a load noticeably above the actual weight of the vehicle while also "passing" the chalk test. With the new LT tires at the same pressure (per chalk test) the load carrying capability was quite a bit less than the P-metric tires at that same pressure. I compromised by putting more air in the LT tires to give me some of the load margin back while running them only somewhat higher than the chalk test would suggest.