Correct Tire Pressure

[Beardy]

Hi Guys,

I have just bought a 2001 Jeep Wrangler TJ which has Radar Renegade R7 M/T tyres and I was wondering if someone could advise on the correct tyre pressure for road use please. I’m new to Jeeps and off roading in general so any help would be very much appreciated. Many thanks

 

[MikekiM]

Falken Wildpeaks 33/12.5
Unloaded... 26psi
Loaded... 28psi

 

[TheBoogieman]

Depends on the "TIRE" size.

 

[Jerry Bransford]

Depends on the "TIRE" size.

X2, what is your tire size @Beardy? And on its sidewall it also says its Load Rating, is it C, D, or E? Finally do you know your wheel width? All of those affect what good air pressures to run.

 

[Beardy]

Sorry guys probably should have mentioned that in the original post. The tyre reads LT285/70R17 121/118Q

 

[Jerry Bransford]

Look for its Load Rating on the sidewall, is it C,D, or E? And your tires are roughly equivalent to a 33" so 26 psi when lightly loaded and 28 psi when fully loaded is typical but that's with a C load rating which is appropriate for a TJ. With metric tires like yours the stiffer D and E load ratings are common and slightly lower pressures work better for them since they are stiffer.

 

[JMT]

Sorry guys probably should have mentioned that in the original post. The tyre reads LT285/70R17 121/118Q

View attachment 485338

That’s a metric equivalent of a 32,7x11.2, so proper pressure is 26psi. If you are fully loaded with passengers and gear 28psi.

You may want to hook up with @UKTJ if you can. He’s a very knowledgeable member in your neck of the woods.

 

[Beardy]

X2, what is your tire size @Beardy? And on its sidewall it also says its Load Rating, is it C, D, or E? Finally do you know your wheel width? All of those affect what good air pressures to run.

Tyre load rating is E and the width is roughly 30 inches

 

[Beardy]

Look for its Load Rating on the sidewall, is it C,D, or E? And your tires are roughly equivalent to a 33" so 26 psi when lightly loaded and 28 psi when fully loaded is typical but that's with a C load rating which is appropriate for a TJ. With metric tires like yours the stiffer D and E load ratings are common and slightly lower pressures work better for them since they are stiffer.

Yes the tyre says the load rating is E

 

[Jerry Bransford]

An E is really stiff so I'd probably try 23-24 psi and see how it looks and ride. And I'll guarantee your wheel width is not 30" lol, more like 7, 8, or 10".

 

[Beardy]

Look for its Load Rating on the sidewall, is it C,D, or E? And your tires are roughly equivalent to a 33" so 26 psi when lightly loaded and 28 psi when fully loaded is typical but that's with a C load rating which is appropriate for a TJ. With metric tires like yours the stiffer D and E load ratings are common and slightly lower pressures work better for them since they are stiffer.

Yes the tyre says the load rating is E

An E is really stiff so I'd probably try 23-24 psi and see how it looks and ride. And I'll guarantee your wheel width is not 30" lol, more like 7, 8, or 10".

yes sorry I meant around 30cm not inches just got the tape measure out and they are 10 inches.

 

[Jerry Bransford]

Yes the tyre says the load rating is E


yes sorry I meant around 30cm not inches just got the tape measure out and they are 10 inches.

That's pretty wide, I wouldn't air them down too much for offroading.

 

[Beardy]

That's pretty wide, I wouldn't air them down too much for offroading.

So would you say 24 psi for on the road?

 

[Jerry Bransford]

So would you say 24 psi for on the road?

24 psi is definitely something I'd try for pavement. When I mentioned airing down for offroad use that's normally down in the 11-13 psi range, I'd probably not go any lower than 13-13 or so with your 10" wide wheels and stiff E rated tires.

 

[James9100]

24 psi is definitely something I'd try for pavement. When I mentioned airing down for offroad use that's normally down in the 11-13 psi range, I'd probably not go any lower than 13-13 or so with your 10" wide wheels and stiff E rated tires.

What’s the lowest you’d recommend safely airing down to offroad with 33x10.5 tires on 15x8 wheels? Non-beadlock.

 

[Beardy]

Amazing!! Thank you very much for your help it’s very much appreciated

24 psi is definitely something I'd try for pavement. When I mentioned airing down for offroad use that's normally down in the 11-13 psi range, I'd probably not go any lower than 13-13 or so with your 10" wide wheels and stiff E rated

 

[Jerry Bransford]

What’s the lowest you’d recommend safely airing down to offroad with 33x10.5 tires on 15x8 wheels? Non-beadlock.

12 psi would be fine.

 

[NashvilleTJ]

Why guess? I suggest doing a chalk test.

Get a big hunk of white sidewalk chalk. Chalk a line an inch or two wide across your tire tread. Drive a hundred feet or so. Look at how the chalk line wears. If it wears away in the middle, you have too much pressure. If it wears away at the edges, you have too little. The proper pressure will wear the line equally across the tire.

 

[Jerry Bransford]

Why guess? I suggest doing a chalk test.

Get a big hunk of white sidewalk chalk. Chalk a line an inch or two wide across your tire tread. Drive a hundred feet or so. Look at how the chalk line wears. If it wears away in the middle, you have too much pressure. If it wears away at the edges, you have too little. The proper pressure will wear the line equally across the tire.

Not everyone has the knowledge or common sense to be able to do the chalk test correctly. Many believe the chalk is supposed to be worn off evenly across the entire tread which is not true. Setting the air pressure to do that will result in a severely underinflated tire. The chalk should not be worn away from the edges of the tread during the chalk test, the tread's edge only comes in contact with the road surface under hard cornering.

 

[Beardy]

Not everyone has the knowledge or common sense to be able to do the chalk test correctly. Many believe the chalk is supposed to be worn off evenly across the entire tread which is not true. Setting the air pressure to do that will result in a severely underinflated tire. The chalk should not be worn away from the edges of the tread during the chalk test, the tread's edge only comes in contact with the road surface under hard cornering.

Do you use a digital tyre inflator at home? Can you recommend a good one?