Correct tire preasure

[Richard B.]

I have a 69 Big block. I'm running some P235/60 HR15 when I drive it to local shows. The manual states that the tire pressure for the F70-15 should be 24 PSI all around. I'm wondering if with the newer radials should the tire pressure remain the same or should I be running a higher pressure?

[Michael A.]

Re: Correct tire preasure

I have a 69 Big block. I'm running some P235/60 HR15 when I drive it to local shows. The manual states that the tire pressure for the F70-15 should be 24 PSI all around. I'm wondering if with the newer radials should the tire pressure remain the same or should I be running a higher pressure?

Richard - I run my 215/70 R15s at up to 35psi and am very happy with it. I believe you will find that radials are better suited for higher inflation pressures. You should check the archives for some more details. You'll likely find some good threads on this topic.

[Michael A.]

Re: Correct tire preasure

Richard
The archives have lots of good stuff in them. Check out this link:

https://www.forums.ncrs.org/showthread.php?t=21451&highlight=tire+pressure+recommendation&uid=5222

It's got some good recommendations as well as some logic behind it for radial tires.

Cheers,

[Duke W.]

Re: Correct tire preasure

GM recommended tire pressures of the era were low to promote smooth ride; 24 psi is sufficient to support the load of either the OE or your replacement tires, but will not offer optimum handling and best fuel economy. Everyone knew way back when to run higher than OE recommended pressure if you wanted to maxmize handling performance.

For the size you are running I would suggest 36 psi. As a general rule, lower profile tires like higher pressure and I recommend 32 for repro tires or 75 and 70 series radials.) If the ride isn't excessively harsh you might even go higher, but don't exceed the placarded maximum cold pressure on the sidewall, which for those tires is probably 36 psi, but might be as high as 44 psi.

Always set pressure with the tires cold and not in direct sunlight. Driving will increase tire pressure by 4-8 psi. Hot lapping race tracks will increase tire pressure by 8-12 psi. These are normal increases and are not excessive. The sidewall placarded pressure is the maximum recommended cold inflation pressure and the above increases based on driving conditions are normal.

Corvettes have a lot of tire load margin (unlike a lot of SUVs). The maximum load/cold pressure is placarded on the sidewall, and for typical Corvette replacement tires, either repro or modern radials, the maximum load capacity (at maximum cold inflation pressure) is nearly double curb weight and at least 50 percent more than gross weight, so you don't have to run relatively high pressure, but it will provide better performance and fuel economy.

Duke

[Richard B.]

Re: Correct tire preasure

Thanks Duke, I used Mike's link and found another thread on the subject, where if I understand, you stated that for BB you can run 2-4 lbs higher on the front.

My 69 is an L68 soi'm going to try 34 front and 32 read for a few trips to see how it feels.

Thanks

[Michael A.]

Re: Correct tire preasure

Thanks Duke, I used Mike's link and found another thread on the subject, where if I understand, you stated that for BB you can run 2-4 lbs higher on the front.

My 69 is an L68 soi'm going to try 34 front and 32 read for a few trips to see how it feels.

Thanks

Richard
Glad to hear you used the link. The Archives are great. I'm in there now looking at postings from 2004 - 2008 regarding epoxy coatings for garage floors. Great stuff to think about for spring projects now that the weather is getting better .... if I ignore to forecast tonight for 7" of snow

To use the archives you just click on "Search" in the second blue bar at the top of the page. The search engine works well and returns meaningful results.

Good luck with your new inflation pressures. I know you'll find them a LOT better than 24#.

Cheers,