I just Installed my new Wheels/Tires yay! now whats the right PSI?
03-22-2012, 01:20 AM
#26
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'08 C300 Lux Barolo Red Beige Leather P2 MM 18" wheels '84 944
You are incorrect in your interpretation. When I posted 28/33, for example, this is standard terminology and means front/rear.
03-22-2012, 01:58 AM
#27
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2011 C300 Sport, 2007 Nissan Titan Crew Cab
03-23-2012, 01:34 PM
#28
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2004 Mazda6, 1993 RX7
Very good selection, capable of car's max load capacity.
You have 225-40-18 XL 92W (with no "P" prefix for 225, ie not P225).
Tire load capability is based on all these factors:
P ---- (or no P for euro-metric )
XL -- Load Design (XL vs SL)
92 -- Load max capacity
psi -- Inflation Pressure
Using the standard tire table, oem per-tire load capability at your listed pressures:
F --- 225-45-17 91 H SL 30psi --- 1179 lbs
R --- 245-40-17 91 H SL 35psi --- 1268 lbs
Your new tires are 225-40-18 92 XL
For the same load ratings as the oem set-up:
F = 34.5 psi
R = 39 psi
---------------------------
The door jam plackard info is dictated by a Federal Statute, and assumes the car has 5 guys in the car with several hundred lbs of luggage in the trunk. This is a very rear biased load condition, and is why the plackard shows higher rear pressures.
For mostly 1 or 2 peps in the car, you can use the rated front pressure all around, but I would not generally go below 32 psi. For the 08 lux, in spite of the plackard pressures, I put about 33 psi all around, for even tire wear.
.
You have 225-40-18 XL 92W (with no "P" prefix for 225, ie not P225).
Tire load capability is based on all these factors:
P ---- (or no P for euro-metric )
XL -- Load Design (XL vs SL)
92 -- Load max capacity
psi -- Inflation Pressure
Using the standard tire table, oem per-tire load capability at your listed pressures:
F --- 225-45-17 91 H SL 30psi --- 1179 lbs
R --- 245-40-17 91 H SL 35psi --- 1268 lbs
Your new tires are 225-40-18 92 XL
For the same load ratings as the oem set-up:
F = 34.5 psi
R = 39 psi
---------------------------
The door jam plackard info is dictated by a Federal Statute, and assumes the car has 5 guys in the car with several hundred lbs of luggage in the trunk. This is a very rear biased load condition, and is why the plackard shows higher rear pressures.
For mostly 1 or 2 peps in the car, you can use the rated front pressure all around, but I would not generally go below 32 psi. For the 08 lux, in spite of the plackard pressures, I put about 33 psi all around, for even tire wear.
.
