fatboy999

I'm running P215-70R15 BFG Radial T/As on my '68 roadster and wonder what tire pressure should I be running?

lars

If 30 people answer your question, you will get 30 different answers. The answer is, "whatever pressure gives you uniform tire wear with good cornering performance." In my experience, on the front-heavy C2/C3 Vettes, that ends up being about 40 on the front and 30-35 on the rear. That BFG tire has a tall, soft sidewall, so you need the pressure to keep it from "rolling under" on hard cornering.

There will now be 29 people who will disagree and have different suggestions for you. All of the answers will be correct.

Lars

Strokemyaxe

7T1vette

The only input I will add is that 25 psi is too low for radial tires on a C3. Somewhere around 30 psi (depending on variable listed by Lars and others) is a good starting point.

george2066

the door sticker is a ridiculous 20 front 26 rear, tried it, it was so bad

Strokemyaxe

CanadaGrant

Max psi for a BFG T/A is 35 psi. Even though it's like riding on a donut or trying to stand on two basket ***** compared to the new gen low profile tires, I would not go over that. I run 32 front and 30 rear in my 69 big block and 30 all around in my wife's 78 small block. Tire performance on uneven or crowned roads leaves a lot to be desired with tall sidewalls....

7T1vette

The low psi spec on the door stickers was a total FUBAR by the US auto makers when they first installed radial tires. Europe knew what pressure they needed, but US knew "better", did the pressure-to-load calculations and wound up with specs WAY to low for radial tires. They found out when LOTS of tires blew out on new cars under extended driving conditions. The OVER-flexed sidewalls OVER-heated and blew out. Pressure specs for mid-late 70's cars were revised upward, significantly.

Strokemyaxe

Bikespace

I won't disagree with Lars on this one. 40 front, 35 rear for radials sounds pretty good. For Autocrossing on BFG Radial T/As (same tires, not a C3), I set them to max rated sidewall pressure, which I think is 44 psi (please check!). Don't expect to have much wet traction with these tires, but the rest of your car will melt in the rain, so it's best to only drive a C3 when the sun is shining.

bashcraft

Yes.

pws69

EXACTLY!! And PRECISELY why the Chevy Corvair was declared "Unsafe at any speed" by the idiot who ran the tire pressure WAY too low (and according to the manufacturer!!)......

revitup

That's actually not true. It was deemed unsafe because of a design flaw in the rear suspension having nothing to do with tire pressure.

7T1vette

It was killed by negative publicity and unnecessary public disdain. Could the Corvair have been designed better? Yes. About every car ever made could have been designed "better".

Public opinion matters...and biased media can sway public opinion. That's what we are dealing with these days! Facts are irrelevant when emotions get cranked up....

Bikespace

I swear I didn't mention Corvairs! The car I was referring to was a Corvair, but I didn't say anything about Corvairs! The late model Corvair had basicallly the same swing-arm suspension as a Corvette. I ran mine with a custom built (by me) heim-jointed strut rod setup, with an adjusted inboard pivot hole at the differential (transaxle, really). It had coils instead of a leaf spring, but it was otherwise very similar to the setup on a C3. With the engine weight behind the rear wheels, and no sway bar (oops), I could lift the inside front wheel on a hard corner and turn with the throttle. I had 225-60R15 wheels in the back, and the max pressure helped with the sidewall deflection.

The early Corvair had a swing-axle design that was much less sophisticated, and could cause issues with underinflated tires and hard cornering. I knew someone who autocrossed an early model. He was much quicker than I ever was.

CanadaGrant

My BFGoodrich Radial T/A's say on the sidewall "240kpa/35 psi max press". I guess I must be missing something...?