Tyre pressure and lug nut question

[purple charlie]

Im running image alloy wheels with 255/45-zr18 front and 295/35-zr18 rear tyres.
Any ideas to the pressures as all books say is refer to door sticker, mines been resprayed.
Also , manual says lug nuts to bee 100 lbft. No steel inserts in wheels so is 100 ok.
Thanks

 

[Roscobbc]

If its any help......I'm running 32 psi front and rear on my 3500lb BB C3 with 255/45/18 front, 285/40/18 rear after being advised by tyre supplier to increase manufacturers recommended pressures for stock 15" wheels by 5 psi for every increased inch in wheel diameter. Can't help on wheel nut torque - I have allow wheels and simply using a 20" telescopic extending wheelbrace.....no torque settings.

 

[Chevrolet]

after being advised by tyre supplier to increase manufacturers recommended pressures for stock 15" wheels by 5 psi for every increased inch in wheel diameter.

Interesting "rule of thumb" there!

 

[Chevrolet]

Any ideas to the pressures as all books say is refer to door sticker, mines been resprayed.

For the original 255/50/16s on a '87 it was 35 lbs PSi:
1987 Chevrolet Corvette tire and wheel sizes, bolt pattern and tire pressure.

How comfortable is the ride at the mo, saying as the car has +2" diameter wheels, lower profile tyres and wider ones at the back? That also depends on whether the car has the stiffer Z51 option suspension, including (yellow) Bilstein shocks and quicker steering. An '87 might also have the Z52 option, which is the suspension of the base/stock car, but has the chassis reinforcements introduced on the '86 convertible.

 

[teamzr1]

From GM Engineering, I selected a 1992 C4

 

[purple charlie]

thanks Roscobbc
just wondering if you meant 42psi? 5psi per 1 inch would be 15psi , what is standard 30?

 

[purple charlie]

For the original 255/50/16s on a '87 it was 35 lbs PSi:
1987 Chevrolet Corvette tire and wheel sizes, bolt pattern and tire pressure.

How comfortable is the ride at the mo, saying as the car has +2" diameter wheels, lower profile tyres and wider ones at the back? That also depends on whether the car has the stiffer Z51 option suspension, including (yellow) Bilstein shocks and quicker steering. An '87 might also have the Z52 option, which is the suspension of the base/stock car, but has the chassis reinforcements introduced on the '86 convertible.

dont know about the Z51 or Z52 option, but it had the FG3 Bilstein shock option , since been replaced by red Koni shocks.
pressures low 30s last time I drove and felt loose so have just increased to 40 but as no mot cant get out on the road.
original build sticker had QZD P255/50VR16 steel belt radial tyres

 

[Roscobbc]

thanks Roscobbc
just wondering if you meant 42psi? 5psi per 1 inch would be 15psi , what is standard 30?

Yes of course you are correct - as you say 15 psi extra.......for mine 40 psi would be too much......there's enough info related to C4's following my post to give you the best answer I reckon!

 

[teamzr1]

How I set my 1999 C5 as per same setting GM uses for street/Race trims
as to tire (cold) PSI, Shocks and Alignment

.

 

[purple charlie]

thanks for the input.
when I get a chance, will take it out to see if handling better or pressure needs tweaking.
as for the lug nuts, Image say go by the book, so will see what 80-100 provides as dont want to damage the rims.
as an aside, there are two locking nuts to each wheel..