tire pressures

[Arch 93]

My '55 100-4 has 165 R15 86S tires on front and 165 R15 86T tires on the rear. Would appreciate any recommendations as to the correct tire pressure(s).
Thanks in advance.

 

[ThomP]

I run "modern" pressures in my modern tires: 32 LBs front and rear. They wear properly and the handeling isn't as heavy as the "antique" recommendations in the shop manual or drivers handbook.

Anyone else agree/dis-agree????

 

[Randy Harris]

Agree - 32 lbs at each corner (Yokohama A321 185.70.15)
Randy

 

[Arch 93]

Thanks for your help, guys. Since we're having very unseasonably warm weather here, getting air in the tires will be a good excuse for a drive tomorrow.
Thomas

 

[Editor_Reid]

[ QUOTE ]
Would appreciate any recommendations as to the correct tire pressure(s).

[/ QUOTE ]

I don't know about "correct" tire pressure, but I like to run at the maximum recommended pressure, as shown on the tire sidewall. This gives best performance, at least in dry conditions.

Yes, it would be high for wet conditions, but I don't drive "spiritedly" in the wet. For that matter, I don't drive my Healeys in the wet at all, if I can possibly avoid it.

Yes, it increases tire wear a tiny, tiny bit, but if you're that concerned about tire wear, you shouldn't own/drive a performance/sports car.

On the other hand, there's nothing wrong with 32 PSI - or something close to that - for a good, general-purpose inflation pressure.

 

[Keoke]

Hi TomSpeer, Neglecting performance and considering driver comfort only. I would suggest a pressure of 28 PSI given you are running the series 80 tires on original width rims..--Fwiw--Keoke

 

[tahoe healey]

PSI at sea level. What about us up here at 6500 ft.? I try to run 30 up here.

 

[Dave Russell]

Atmospheric pressure at 6,500 ft would be about 79% of what it would be at sea level.
For the same "actual" pressure, the tire would be inflated more at higher altitude.

HOWEVER, simple tire pressure gages would also read higher at higher altitudes, & the two changes would likely compensate for each other. Result - No change.
D

 

[Dave Russell]

[ QUOTE ]
[ QUOTE ]
Would appreciate any recommendations as to the correct tire pressure(s).

[/ QUOTE ]

I don't know about "correct" tire pressure, but I like to run at the maximum recommended pressure, as shown on the tire sidewall. This gives best performance, at least in dry conditions.

On the other hand, there's nothing wrong with 32 PSI - or something close to that - for a good, general-purpose inflation pressure.

[/ QUOTE ]
Hi Reid,
My below statements are general statements. Optimum tire pressures will depend on the exact car, exact tire design, & intended use.

Running max sidewall rated pressure will likely not hurt anything on RADIAL tires, except for a harder ride. Inflating BIAS PLY tires above the pressure needed for the load WILL cause the tires to hump up in the center & reduce the contact patch.

On radial tires, higher inflation pressures usually increase the tire's grip. The BN1, BN2 with it's more rearward weight bias can be better balanced - oversteer/understeer - by higher pressure, more grip in the rear, lower pressure in the front. With a 3/4" front sway bar, I find that 28 front, 32 rear gives more neutral handling. Keeps the rear from coming out as much.

The sixes with more front end weight usually work better with more equal front & rear pressures.

The very low original "book" pressures for bias ply tires are too low for modern radials & will give much reduced stability. OTOH, Higher pressures in bias ply tires will just make them hump up in the center & reduce the contact patch. As you say, it depends on the tire & it's intended use.
D

 

[Johnny]

I am using Dunlop 165SR/15 86S type tires. I tried 32 psi and found the ride very hard and undesirable. By lowering the psi to 28 it seems to make a difference in less harshness. I also found that by running at higher psi the sidewall developed a depression in it that I didn't care for, but not on all 4 tires. It might have been a defect in the tire but at any rate I chose to lowere the psi, the depression didn't change all that much but it made me feel safer anyway.
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