Tire pressure

[bojaq1@gmail.com]

New to forum in CT.

"64 Spyder convertible.
The manual says 15 psi front tire pressure and 26 psi rear. This of course is for belted tires. It seems low for the radials I'm running now. Any thoughts?

Bunker

[RexJohnson]

10 psi less in the front works good.

[RexJohnson]

10 psi less in the front works good based on the load rating of the tires that you are using.

[bbodie52]

Welcome to the Corvair Forum!

Sizing Corvair Wheels and Tires
http://autoxer.skiblack.com/tires.html

Tire pressure

The factory recommended tire pressure settings were selected to dial in understeer and provide a comfortable ride on bias ply tires being the important conditions. Although radial tires are much more forgiving, you should still maintain a pressure differential of 8 to 10 pounds front to rear, but you can improve the responsiveness and handling by raising the tire pressure up to about 27 front, 35 psi rear for street use (don't exceed the maximum tire inflation on the sidewall). Autocross use is a bit trickier, as the construction of the tire has an effect on the amount of pressure in the tire. In short, there are now three types of "Street" tire:

Real Street Tires
The first are tires to drive around on all the time, these are designed to give a reasonable service life (~50k miles), good all weather performance, and perhaps a sporting amount of grip. The BF Goodrich Radial T/A, Goodyear Eagle Aquatread, etc. fall into this category. These tires have a relatively soft sidewall which gives them a nice ride, but they unfortunately allow the tire under hard cornering to try to roll under the rim, meaning you're now cornering on the sidewall instead of the tread. Bad plan.

The proper solution is to get a set of competition tires (see below) which don't do this. But if you're just trying out the sport, there is a band aid fix - more air. The additional pressure will stiffen the sidewall, which will help the handling, up to the point where the contact patch is so much smaller that the tire slips anyway. Generally, a 5 to 10 psi increase works well, *but* you may need to increase the front and rear tires different amounts to make the car well-balanced.

https://ssl.corvair.com/user-cgi/catalo ... w_page=392

TIRE PRESSURE: We suggest the following cold pressures. These may need to be higher with new tires designed for higher running pressures. Cars – Front 20-22 lbs. Rear 28-32 lbs. Vans – Front & Rear 28-32 lbs.

I also installed a very good Tire Pressure Monitoring System (TPMS) on the center-top padded dashboard, just under my windshield-mounted TomTom GPS system. It is very easy to mount and uses no adhesives to bond to the padded dash. No wires either, as it contains rechargeable batteries and is solar powered. It automatically turns on when the wheels turn and each sensor begins sending tire pressure data, and automatically turns off when you park the car. The illumination system also automatically comes on at dusk.

Tymate Tire Pressure Monitoring System-Solar Charge, 5 Alarm Modes, Auto Backlight & Sleep & Awake Mode, Tire Position Exchange, with 4 External TPMS Sensors (0-87 psi)

$79.99

https://www.amazon.com/gp/product/B07S7 ... UTF8&psc=1

[gbullman]

The easy recommendation with radials is 22 front, 32 rear and always 10 PSI. More in the rear than the front. Generally that 22/32 is good for most people. If you like to push the car a bit harder, especially in turns you can experiment with pressures and see what feels best to you. I landed at 23 and 35, just felt more balanced in turns to me at those pressures.

[RexJohnson]

The numbers need to match the tire. Some have a max pressure of 44 psi and others are 32 psi. So just a standard number doesn't work.

[Frank DuVal]

I agree, the sidewall ratings should be followed, but usually the weight of a Corvair is no where near the need to run the maximum pressure, but in the case of max 32 psi tires I'm there or higher in the rear, so, what numbers on the sidewall? Obviously I'm doing it wrong....

There are all sorts of methods to see how well inflated a tire is (not over, not under) in the vehicle in question, chalk, powder, how it is wearing, etc etc. A Google search can keep you busy for days.

I just go with 10 psi higher in the rear and drive on.

[66vairguy]

Good comments. Keep in mind on new cars the maximum COOL and HOT rating is usually posted on the body door frame or in the manual and often different than maximum tire pressure. Since the Corvair is older some guesswork is needed.

The maximum tire pressure ON THE TIRE is just that! If a tire says MAXIUMUM 35PSI that means the when the tire gets HOT which, according online articles, is 4 to 6 PSI more then when the tire is COOL.

The other issue is running bigger tires on the rear of a Corvair vs. the front. Since this SHOULD result in improved rear traction you can run a smaller front to rear pressure difference.

Bottom line - some experimentation is needed depending on the tires used, but you don't want the front tire PSI too low or it will overheat, and you don't want the rear tire PSI too high as this can lead to tire failure.

[joelsplace]

Max pressure on the sidewall is cold. Max pressure isn't that critical either since they can't even be bothered to define cold. Here in TX where you can have 20 degrees in the morning and then 80s in the afternoon will get that pressure way up there hot.
My friend that ran a tire store since the 80s pointed out that the max cold pressure is actually just the pressure that the max rated load was tested at.
Nothing says you can't run more load with more pressure BUT you are taking responsibility for the risk since you are running in untested circumstances.

[vairmech]

First off, what's with all the adds?????

It's been mentioned that you need to look at your tire sidewall max cold pressure. From there I use a ratio formula similar to what the original manufacturer did.

As an example for a 44 psi tire in the front I would not quite go to less than half the pressure but more like 30-32 psi. Bias ply tires had a really stiff sidewall so they could get away with the 15 psi in the front which is about half of the 32 psi max cold they used to have.

Radial tires take more pressure to operate safely than do bias ply tires. Personally I am more performance orient and not the cushy grandma ride for hemorrhoids! I tend to have more tire pressure all around just for handling.

As far as heat goes, yeah, you don't want to check tire pressures that have been out in the sun! At the race track I will cover my tires to keep the sun off so I can check tire pressures, I don't pay to much attention to the outside air temp and put the pressure where I like it.

[Frank DuVal]

What ads? Did you become unlogged in?

[vairmech]

Brad Bodie puts a list of ads in his post that is a mile long!

[Frank DuVal]

YES! It is like Amazon's whole page.

I agree, at least a little over 20 for any radial on the front of a Corvair car. Then fine tune with looking at the tread pattern, chalk, etc and how it feels driving.