Thread: Tire Air Pressure

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Not that I have a deuce, but my '31 roadster is real close in many respects. I just pushed the chassis back in my garage and noticed I had a soft tire. No problem as that tire tends to lose pressure over a few months. But with that said, and it will be permanently fixed, what is a "comfortable" air pressure to run at. SB Ford weight engine/C4 (600#) plus a big Walker A/C radiator, with a '32 15 gallon semi-repro gas tank hung out the back The front tires are 205-60x15 and the backs are 265-60x17. I'm guessing that the tried and true 28# at all four corners might be too much.

start at 30 PSI, do quick burn outs, deflate the tires until the rubber patch is even from side to side :

I'd bet you will end up with "less than" 20# to help with ride. Just look at the sidewalls after you have the car built and at final weight.

There's a trick that I teach to the newbie drag racers who are running street tires. I instruct them to use white shoe polish to paint a line across the tread of each rear tire, maybe two inches wide. I tell them to drive around the water box because all it will do is to waste rubber. Street tires will not get sticky.

Anyway, I'm getting off course. Paint the stripe across both rear treads, let it dry, make a pass and stop at the big end, off the track of course, then inspect the stripe. If it's worn off at the edges, the tire needs more pressure. If it's worn off in the middle, the tire needs less pressure.

The same thing might work for determining optimum pressure on the street. Paint a tread stripe on all four and take a tour, going around corners, etc. This won't necessarily lead you to the optimum ride quality, but it should lead you to the best handling and tire wear characteristics.

Hey my rubber patch even side to side now. Dropped mine down 28# get better bite with street tires and smooth ride.

Each tire is a law unto itself.

All tires are BF Goodrich.

That said, my 32 runs 195/70R-14 on 5 1/2" wide wheels in front at 30# and occasionally at 28#.

Rear is 285/70R-15 on 10" wide wheels in back at 20#.

When I ran a similar size back tire - 31.50x15 light truck tire I ran it 12# - 16#.

Rode good and no probs with either rear tire wanting to roll off the rim.


You can duplicate the burnout bit by simply rolling the car through some water on a smooth cement driveway and noting the pattern left.
Same rule as Tech gave vis a vis patterns vs pressure.

Well - it for sure sounds like I go out, stand on the throttle and see what the rubber patch looks like (that is if that li'l 302/C4 will spin up that hard with the 90/10 gas)

Also, it should PO the Statie with the stupid yappin' dog that lives across the street, and the other a block away and the next other around the corner

You shouldn't have any problems with your 302.

My pals bulbous wonder shown here in the pic . . .



. . . gets yanked down the highway pretty good with his 302.

And that's taking into consideration that the tune-up really isn't up to snuff yet.

When he got the car, the mild cam was a tooth off and it's running a single plane intake with 600 cfm Holley double pumper.

He got the cam bit straightened out a couple weeks back then got a new double plane intake with 600 cfm Edelbrock.
Two Edelbrocks in fact, one from an Ebay seller for a hundre bucks and another for ten bucks cuz the guy didn't know what he had and didn't really care.

Anyway, he left the Holley on the engine until last weekends three day Route 66 Fun Run was done.

I'm gonna head up to his shop today to use his sheet metal shear and brake and see if he's finished the intake/carb swap.

Originally Posted by C9x

You shouldn't have any problems with your 302.

My pals bulbous wonder shown here in the pic . . .


When he got the car, the mild cam was a tooth off and it's running a single plane intake with 600 cfm Holley double pumper.

He got the cam bit straightened out a couple weeks back then got a new double plane intake with 600 cfm Edelbrock.
Two Edelbrocks in fact, one from an Ebay seller for a hundre bucks and another for ten bucks cuz the guy didn't know what he had and didn't really care.

Anyway, he left the Holley on the engine until last weekends three day Route 66 Fun Run was done.

I'm gonna head up to his shop today to use his sheet metal shear and brake and see if he's finished the intake/carb swap.

Those mods should help his "land barge" out a lot.

I would guess mine with the E-brock Performer RPM and 600CFM along with a Ford SVT "E" roller camshaft and 1.7 rockers, full MSD ignition and a 2200 RPM TCI converter should move my 2500 (or less) car then - that is if I can still afford to put gasoline in it

It's a 46.

Shouldn't be a prob, he's a good guy and I shot the pics.

The back seats in these things are a drive-in-movie delight.

Now he's got a 46 Club Coupe in his shop.
An old hot rod, the SBF got yanked and an SBC is going in.
He's buildng motor mounts for the owner.

Just out of Oatman, Arizona.
Small gold mining town, burros, re-enacted gunfights, etc.
Cool place.
It was one of the stops on the last day - last Sunday - of the Route 66 Fun Run.


Burros.
Note the vertical stripe near the front legs.
Supposed to indicate lineage from the donkey/burro Mary rode on her way to Bethlehem.


Just before the side by side pic was shot.
On the way to Rosie's Cafe on Hwy 93 about 20 miles south of Hoover dam.
They have a pinstriper on duty there.


A junkyard just south of Rosie's.


No other pics converted to JPGs right now.
I'll shoot a bunch of pics for you next time we hit donut run.
Probably a week from Saturday.
This weekend has car shows at all the casinos in Laughlin.
We're going to hit it tomorrow.

Cool place, couple weeks back was the River Run for Harleys etc.

Hey Dave, 9.5 in the rear and 32 in the front works good at the dragstrip!!!!!!

Remember to let a half pound out of the rear when the track gets hot and slicks up in the afternoon though!!!!!!

As one old wizened and very knowledgable Hot Rodder and Drag Racer extrodinaire told me many years ago, "If you can't race it or take it to bed, you don't need it!"...

None of this has a thing to do with your current question, but I've had a bad day and coherency is not my strong suit!!!!!!