What tire pressures for 16" fuchs

[Tidybuoy]

I'm just wondering what tire pressures people are running for around town driving.

I ask because the factory stickers on my car are for 15" wheels with 185's. My car has 16" Fuchs 6&7. Since it's a mid/narrow, I'm running 195/55/16 & 205/50/16 which fill the wheels very well.

I recently got new tires and the mechanic asked me my pressure preference and I had no idea - I've only had the car for 4 months.

Thanks.............Vern

[HarryD]

Vern:

I have 205/55-16's on my '73 and for the street run 29 psi front, 34 psi rear and it seems to work well.

[kyle242gt]

29/34 is the spec for my 80; I find it a little hard, but that may be the tires (all seasons up front, and 15 years old in the back, I know I know).

The PO had them 5+ PSI lower all around. Rode nicer for sure.

[Flat Six]

+1

29/34

205-55-16/225-20-16
7/8X16 Fuchs

[mystro]

is 29/34 the same for 15" tires?? Just curious.

[db_cooper]

It is worth experimenting with tire pressures. Modern tires run higher pressure than the 25 year old tire designs.

Modern tires may have the maximum load rating at 45/55 psi or more.

Older designs were load rated at a lower PSI.

Our cars are light..and don't need to be pumped up to the maximum pressures. Higher pressures than the owner's manual may be called for.

Old school indicator for high tire pressure was the center section of the tire wearing faster than the outside edges.

These days that very well may indicate too low a tire pressure, as centrifugal force will expand the inside of a modern tire at speed..thereby wearing it more quickly.

I run mine close to 35/44.

[HarryD]

Originally Posted by mystro

is 29/34 the same for 15" tires?? Just curious.

That is what is called out for my original sizes (165-15 185/70-15).

For 1978 to 83 the decal looked like this:

[HarryD]

Originally Posted by db_cooper

It is worth experimenting with tire pressures. Modern tires run higher pressure than the 25 year old tire designs.

Modern tires may have the maximum load rating at 45/55 psi or more.

Older designs were load rated at a lower PSI.

Our cars are light..and don't need to be pumped up to the maximum pressures. Higher pressures than the owner's manual may be called for.

Old school indicator for high tire pressure was the center section of the tire wearing faster than the outside edges.

These days that very well may indicate too low a tire pressure, as centrifugal force will expand the inside of a modern tire at speed..thereby wearing it more quickly.

I run mine close to 35/44.

Interesting. For Autocross, I ran my street tires at 34/39 to get the best contact patch. Higher pressures resulted in lower times and lower pressures had the tires rolling over onto the sidewalls.

[db_cooper]

Originally Posted by HarryD

Interesting. For Autocross, I ran my street tires at 34/39 to get the best contact patch. Higher pressures resulted in lower times and lower pressures had the tires rolling over onto the sidewalls.

Yep..modern tires need more air pressure. You don't see many steel belted radial tires anymore either.

The factory 29/34 decal would be at the lower range of what you want to run these days. Most tire sidewalls will squirm at those pressures or lower.

[HarryD]

Originally Posted by db_cooper

Yep..modern tires need more air pressure. You don't see many steel belted radial tires anymore either.

The factory 29/34 decal would be at the lower range of what you want to run these days. Most tire sidewalls will squirm at those pressures or lower.

No so sure about higher pressures for street driven tires.

For non-Autocross driving, factory pressure seem about right for my car. I do not see the tire wall rollover from too low of a pressure and the wear patterns appear to be normal (i.e. even across the face of the tire).

[Quicksilver]

"Proper pressure".
Proper pressure for what? Max grip? Max comfort? Max fuel economy? Max tread lifetime? What kind of surface and conditions.?

The door pressures are a good place to start and if that is good enough then you are done. If you want some "extra" something you will have to play around and experiment.

Different types of tires have different needs. Most tires with a street tread will get maximum grip when inflated to higher pressures. The increased pressure stabilizes the tread blocks to maximize grip. It isn't uncommon to see maximum dry grip on a street tire when it is inflated to about 5 psi above the maximum pressure posted on the side of the tire.

Race type tires are usually the opposite. They have huge tread blocks (or none at all) and you lower the tire pressure to increase tire compliance.

In the rain you increase the pressure to make the contact patch as firm as possible as any compliance will reduce the squeegee effect you are looking for.
In snow you also go higher pressures to try and induce the treads to cut down through the fluff and get a purchase on whatever hard surface can be found.
In sand you drop tire pressures to try and distribute the load and keep from sinking in.
And in dirt... Never competed on dirt so I really don't know. I suspect it is highly variable depending on the exact tire, and the type and compaction of the dirt.

[nineball]

i agree you should experiment with various pressures until you get one you like. the old trick was to draw a chalk line across the tread on each tire then roll the car back and forth over the line a few times. if the wear line is even you are good. if it wears off more in the middle you have too much pressure, more on the ends and you don't have enough.

[db_cooper]

A good place to go is look at the sidewall of your tire(s) and note the load rating at what PSI. Something like" max load 1124 lbs at 44psi" (it will have metric specs too)

That is the high water mark for tire pressure.

911s are pretty light, especially in the front, however the tire design may not like running at 29psi which is about 40% below the maximum rated pressure.

It all depends, and part of the joy of ownership. Experiment and see.

[Nine17]

I agree that current tire designs are meant to run at higher pressures than tires manufactured when our cars were new. Because of this, you do need to experiment. I bought a little 1hp Craftsman compressor at OSH, a nice wall-mount retractable-reel 50' air hose from Griot's, and a racing tire gauge with a big dial and a bleed-off valve. I don't have to find a gas station.

I've found my sweet-spot is 36 front/40 rear for 205/55-16 and 225/50-16 Kumho Ecsta SPT's on 7 and 8 inch Fuchs. The steering response is terrific, the handling neutral, and the ride is superb on Bilstein HD's and stock torsion bars.

Opinions: like belly-buttons and arseholes, everybody's got one.