[MonopolyBag]

It says wheel pressure should be 29psi, that seems low. The wheels, Dunlop, says 44 max psi. What should they be? They are at 40 psi now. They were like this since I bought them. Should they really be 29?

2004 Forester XS

 

[lh0628]

Yes for stock size, but you can play with the psi to find a combo that you like. I wouldn't go anything bigger than 4-5 psi difference front vs back.

40 is pretty high.

 

[2.5x_sleeper]

Lots of threads on tire pressure. Here's one to start with. Want more, try a forum google search on "tire pressure" (without the quotes). :wink:

I run 36F/34R, which seems to be the "sweet spot" for my Toyo Proxes 4 tires & suspension setup. :smile:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]

 

[funkymonkey1002]

Like bobby I found 36f/34r to be a pretty good all around pressure for the stock size tires. On some of my 17" tires I ran up to 42 psi (on tires that were 50psi max, I wouldn't go any higher than 90% of the max pressure). Anything higher than around 38 I found to be harsh and anything under about 32 or 33 felt too squishy. I'd recommend around 2 psi higher in the front, unless towing or carrying a lot of weight in the back in which case you would bump up the rear pressure.

 

[crewzer]

More info here.

Assuming the tires are "Euro-metric" (no "P" designation before the tire size), their maximum load specification is based on 36 psi cold inflation pressure.

Inflation pressures higher than 36 psi don't increase the load capacity. Instead, a higher "max press" spec of 44 psi allows for "special applications", such as sustained high-speed driving, where the manufacturer recommends higher-than-normal tire pressure.

For example, here's some guidance from Michelin:

For high-speed driving, additional inflation pressure and possibly reduced tire loading and/or upsizing is required. In the absence of specific recommendations by the vehicle manufacturer, use the following guidelines based on those in the European Tyre and Rim Technical Organization Standards Manual.

For speeds over 160km/h (100 mph), load and inflation must be adjusted according to the table below.

H-Speed Rated Sizes:

Maximum Speed (mph) 100 106 112 118 124 130
Inflation Increase (psi) 0.0 1.0 2.0 3.0 4.0 5.0

Load Capacity (% of max.) 100 100 100 100 100 100


V-Speed Rated Sizes:

Maximum Speed (mph) 100 106 112 118 124 130 136 143 149
Inflation Increase (psi) 0 1 2 3 4 5 5 5 5

Load Capacity (% of max) 100 100 100 100 100 100 97 94 91

Subaru's 29 psi cold tire spec probably delivers a good balance of ride comfort, fuel economy, handling, and tire life. Higher pressure will probably increase fuel economy a bit, but may result in a jittery ride.

I presently have my tires inflated to 35F / 33 R, which is 3 psi above Subaru's recommendation for my particular tires.

HTH,
Jim / crewzer

 

[MonopolyBag]

Thanks everyone!