Tyre Pressures

Just put a new set of 19" on the P38. I've noticed that the old rears are wornin the centre and not at the sides. It states 38 psi in the manual but is this too high and gives uneven wear.

search chalk test.....tis the best way to be sure

Yep, 38 is correct for standard 16" wheels/tyres. Search threads on pressures, otherwise someone else with 19's might see and reply!

would love to know correct front and rear pressures for standard 18s also as put my rears on 38 but rides quite harsh now is the book wrong

Check out www.carbibles/tyre_bible for loads of useful info on tyres generally. Not 4x4 specific, but a lot of good sense & a good base to sort out what`s going on with uneven wear patterns.

Ta for the input. 38 is far too much and I'm going to try 28 in the front and 32 in the rears

The handbook say's:

235/70 x 16 radial
255/65 x 16 radial
255/55 x 18 radial
All load conditions.......................Front 28psi / 1.9bar.......Rear 38psi / 2.6bar

(page 179)

Does'nt mention 19ins. So maybe they are different.

My 2 sets of 18's i took off showing classic over inflation (all tread in middle worn away and 4mm on the edges, so something not right.

i run 19s have 32 all round, dont have no problems with them..

I have 19's and run 32 all round normal and 34 on a run or loaded seems good to me

Anyone able to confirm correct pressure on 205/80/16's on an RRC (standard fitment, basically)? 28 front seems low, and 38 rear very high in comparison!!

MikeV8SE said:

Anyone able to confirm correct pressure on 205/80/16's on an RRC (standard fitment, basically)? 28 front seems low, and 38 rear very high in comparison!!

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Probably not. I'd tend to agree with you but then.....


As you've been told before do the Chalk Test.
a search will bring up the procedure then you'll know for sure

I think that particular chalk test is misleading, and not the true chalk test. Hmm...

MikeV8SE said:

I think that particular chalk test is misleading, and not the true chalk test. Hmm...

Click to expand...

Yeah I should have said make sure it's the true chalk test

I have 18 inch wranglers and run 28 front and rear or the centres go on the rears.

ill be leting my rears down in morn as i put them to 38 from 30 as that what my owners manual said but its seems to ride harsher so book must be wrong im running standard size pirelli scorpions

I noticed on the new pirrelli scorpions that i bought that the tread in the center of the tyre is much shallower than the sides and after abot 15000 miles they were nearly down to the wear bars but the outer tread was ok these were run on the front of the car at 28.
I had to replace them after 15000 as 1 got blistered while i was in Macedonia and could not get in touch with the manufacturer so i replaced them with a different make as i need a tyre that lasts more than 6 months

why 38 in the rear? the major lump is in the front.. if they are the same tyres front and rear (which they are out of the factory) then to keep the profile the same surely they should be higher in the front.....

someone give me a physics lesson, im obviously missing something

I got a new set of pirrelies on the front and they showing wear in the middle of the tyre and not on the outside after 1500o miles run at 28 on the front.The toyo open country run on the rear at 38 have lasted twice the milage and showing even wear.
also one of the pirrillis got a blister on the side wall and i had to get some new tyres while i was in Macedonia so could not get in touch with the manufacturer so hd to pay for 2 new tryes of a different manufacturer and i will see how these go.

Try this get some chalk. Put a thick line of it across all four tyres. Drive about 10 revolutions in a straight line. Look at the line on each tyre. If it's lighter in the middle than on the edges, you have too much pressure. If it's lighter on the edges than the middle, there's too little pressure. If it's even across the whole line, you're good to go. Remember tyre pressures are different dependant on the tyre fitted and the load carried also the tyre pressure in the hand book are there not only as weight distribution but also as a steering characteristic you can also do a rough load calc based on max lad tyre can take also remember that the springs front and rear are rated differently to compensate for load distribution