32 psi is the maximum suggested rating, you can always let some out and go softer if you wanted. Ideal would be between 27-32

 

alright will try 27 psi and see if that helps, they need to do some paving on the roads around here!

 

Signed in to this forum to give you an answer.
I live in Holland and once got hold of the system, the car- and Tire-manufacturers in Europe, and since 2005 also in America, use to determine the advice-pressures for radial tires on cars.
Learned myself Excell to make spreadsheets for it and translated a few to English to go worldwide with it.
In the next map on my skydrive of Hotmail,in wich I use the same username as here for my E-mail-adress, spreadsheets and examples for re-calculating tire-pressure advice when other the original tires, but can also be used to check the original and se of you can go lower in sertain conditions.
Recalculating tyre-pressure - Windows Live
Download the spreadsheets and open them in Excell- like programm to work with it, and dont try to open it in the browser, because then it wont work because of protection and data-validation I used in it.
If you cant work it out , give me the needed details and I will do it for you.
From the tires: Maximum load ( Kg, LBS, or Loadindex) and reference pressure ( not the maximum pressure, but it is always the same for a sort of tire.).
From the car : Gross axle weight ratings front and behind ( GAWR) to be found on a plate on the car somewhere. or in the manual.
Maximum speed of car, or speed you sertainly wont go over.
For normal use advice, the way you load your car normally and the empty weight and front or rear drive ( motor front or rear), to estimate the weight distribution.

If you calculated it , with the large wheels I suspect you to have, the advices might be verry low, mayby even that 20 psi you have.

Greatings from Holland, and I hope my information makes things clear for you.

 

Thanks, my grand parents are from Holland! I will try and say thank you in dutch here goes nothing! "hartalik badandkt"

But I don't have excel and cannot open the files, I will get the info for you, maybe you can calculate for me?

 

I would not go below 28psi, you don't want to hump the center of the tire.
or over stress the sidewall.

 

no I don't want that, the odd thing though is that I think they came from the dealer with 20 psi, I just always made sure they were even, I have owned it since new, and thought that was how it was supposed to be!

 

I hate you.







For having the ability to go over 150 with that damn v8! LOL

As my answer, i would not go over what the tires themselves are rated for, nor would I go under that rating. If yoru tires are speed rated for say w then you better not be treating them like there z rated! LOL

 

I hate you.





For having the ability to go over 150 with that damn v8! LOL

As my answer, i would not go over what the tires themselves are rated for, nor would I go under that rating. If yoru tires are speed rated for say w then you better not be treating them like there z rated! LOL

lol I know so how do I know what they are rated for the letter??

 

When i picked up my truck it rode like shit. dumb dealer new truck get ready guy
put 45psi in the tires.

 

what is the speed rating on your tires? must be around 130 mph?? also me door jam sticker says max 32 psi, but the tire says 45 psi max??

 

ok here is the specs continental tires TPC spec 1181 MS P235/50R17 95S AS

GVWR 1996 kg GAWR 1149 kg GAWR RR 1110 kg

lets say max 120 km/hr city what PSI should I run for this?

and 220 km/hr track or desolate highway What PSI should I run for this?

 

If you want to ride 220km/h you have to put other tires under with at least speedrating V= up to 240km/h , your speedrating of the tires is up to 180km/h= S
P stands for standard load tires with reference pressure up to 160km/h of 35 psi , to the American system . AS at the end I dont know what it means.

For up to the GAWRatings , what is nowadays called normal use for up to 4 persons and load
The spreadsheet gives F29psi R 27psi up to 160km/h/ 99miles/h.
Up to 180km F30psi R29 psi
If you are traveling light , say 2 persons and a little load, I estimated the Axle loads on front 1100 and rear 1000kg up to 160 km/h Front 27 and rear 24 psi
the same loads up to 180km 112 miles/hFront 29 and rear 26psi.
Below this there is danger of damage to the tires, you risk tire blew-out.

This proves that 20 psi is too low , and this discomfort belongs to the low side-wall tires you have.
If you want more comfort , you need for instance 16 inch tires with higher side-walls.
I also calculated the pressures for up to 220 when you have V rated tires with the same maximum load of 690kg ( 95 loadindex)
light loaded F32 R29
4pers. and load F 34 R 32.
If you weigh the car or if you give me the empty weight the light load can be saver calculated. But end conclusion , dont drive faster then 180 km/h with these tires.
If your car has a technical maximum speed originally of 220km/h , these tires may not be on the car by law, or it must be wintertires , and then only between october and april here in Europe American law can be different), with warning on dashboard not to go over 180km/h.

Hartelijk bedankt for expressing your appreciation in Dutch.

 

ok my tires a rated for S or 180 km/hr max!! The Z rated tires on my 94 camaro had a limit of 240 km/hr and that was how far the speedo went. I had that car up to that speed a few times that car had no speed limiter!!

 

O4, I have z rated tires on now, and yes it goes to 130mph. bin there, done that
a few times. I always run oversize tires on my trucks. I adjust the press to keep
the tread flat and by years of experience. .you should get the truck weighed.
pickups are always light in the rear end, so you don't need as much psi.
I have 255x45x18 front =35 psi 275x40x18 rear=28 psi handles great.

 

The Zq8 trucks do ride a little bit stiff, I have the stock 18's and usually run around 30-32 in the rear(cant really go any lower or the tire light comes on) and about 34 in the front. I work at a tire shop, and we put different pressures in different vehicles mainly depending on their weight and type of load they carry. we rarely go by the door sticker.

 

Read something about Z rated tires , probably the same as ZR tires speedcode.
This is when the tire-manufacturer did not stay to the standards of the ETRTO or TRA with their tire-build specifications. Then they have to give themselfes the highening up specifications for the reference-pressure for higher speeds.
Mostly they also put a Speedcode-letter on it , like V, W, or Y , then you can use that for it.
Made a picture of how the reference pressure highens up and the maximum load lowers down, for all the speedcodes from S to Y.

So ZR only means this and somethimes when there is also Y on it you can use them up to 300km/h

Second item is your higher GAWR front then rear. You mostly see this with smaller cars ( ford Fiësta for instance). For your car it is probably done to give the possibility to built in a heaviër motor like you did. In the original configuration you probably have about 900 kg on the front eve fully loaded. The GAWRings together are 2260kg and the GVWR is 2000kg.
This gives a extra for loadshifting of 260 kg wich is a comfortable marge, mostly it is only 70kg. The load on the front stays almost the same , extra loading gives almost only weight on the rear. Even the front seated persons have their gravity-point at mosly 1/3 from the front. In the back an load is almost only extra weight on the back.
So that is why I estimate the front at max 950 kg, but only weighing gives sertainty.

 

I want to weigh it anyway just curious how much I added, so I will try and get a weight at a truck scale? maybe I can run 32 up front and 28 in the rear I never carry more than my self, and maybe 50 pounds of tools, and spare parts, luggage etc..

 

scaled the truck today Front 990 kg/2182 lbs . Rear 750 kg/1653 lbs GVW 1740 kg/ 3836 lbs. This was with a driver 165 pounds and 15 gallons of fuel = 90lbs.