Impossible To Find Answer??

[ParadiseXJ]

32


...but I tend to obsess on more important things...phew!!

 

[Ecomike]

32


...but I tend to obsess on more important things...phew!!

LOL, I am feeling the pressure already, and my head is spinning, so I will just chalk up to a long week of fatigue

 

[Tim_MN]

5-90 nailed it. I was too lazy to type all that, and figured that Google knows everything. :search:

2000 and 2001 had some trim packages that came with 16" is true, and they also came with the exact same door stickers as XJ's with 15" rims. As I recall, I ran about 30-33 psi in my 16" tires.

 

[ParadiseXJ]

So what does wheel diameter have to do with tire pressure...I don't mean the little 2" tall ricer tires on 20's, I mean the difference between 15 and 16.

Does anyone really do this? I mean split hairs twixt 30 psi and 32 psi. It's a Jeep, not a Ferrari.

Don't get me wrong, I am amazed by the knowledge...

 

[joe_peters]

Is turning allowed, or must be done in a straight line, or irrelevant?

Thanks for the write up BTW...

Straight line ONLY--when you turn the outer edges of the tires will scrub more.

 

[joe_peters]

So what does wheel diameter have to do with tire pressure...I don't mean the little 2" tall ricer tires on 20's, I mean the difference between 15 and 16.

Does anyone really do this? I mean split hairs twixt 30 psi and 32 psi. It's a Jeep, not a Ferrari.

Don't get me wrong, I am amazed by the knowledge...

It is all about tire wear and fuel mileage.

 

[5-90]

So what does wheel diameter have to do with tire pressure...I don't mean the little 2" tall ricer tires on 20's, I mean the difference between 15 and 16.

Does anyone really do this? I mean split hairs twixt 30 psi and 32 psi. It's a Jeep, not a Ferrari.

Don't get me wrong, I am amazed by the knowledge...

Sidewall height - which has a noticeable change in the supporting effect of the sidewall belts.

(As far as those 2" tall riceboi & lowrider tyres? I don't even know why they bother putting air in them - they're rubber bands! I'm not even sure how they get 'em on the wheels in the first place!)

 

[Talyn]

I'm not 100% sure on this, but the more air space/area between the rim and tire the less air pressure needed to support the same load. For example, the stock PSI is 33 and that works for a stock tire. But on my 31s I have to run around 27psi to get decent wear and a good foot print.

 

[heyhar]

Another thing to consider is the tire's Load Rating. My '96 Country came with 225/70-15 tires, while most other XJs came with 225/75's. The originals on mine were a rating of 100T, with the 100 representing the load, and the T is the speed. I now have 235/70s on it, meaning 10mm wider, but about the same circumference. The problem is that an XJ, normally loaded and driven, isn't heavy enough to need this relative stiffness, so the cure is to reduce the pressure a hair. The door jamb sticker shows only 215/75 tires at two different loads, and suggests 30 PSI for both! I usually run at 32PSI, as a compromise of comfort and MPG, although at 28, they don't appear to be any less inflated.

 

[Ecomike]

Speaking of ricers, LOL, and rubber bands, I had 14" 60s on my 1973 Ford Pinto (I was getting it ready for a V-8 and the drag strip), while it was my DD. I was doing about 70 mph one day on the freeway when I felt something. About 10 miles later I pulled over and discovered one of them was flat. It had so much rubber on the tire, I hardly noticed any difference on the highway at 70 mph,

 

[Tim_MN]

Perform the chalk line test. The results are valid for any tire/rim combination. Adjust your tire pressure a few psi +/- to meet your individual needs.

It ain't Rocket Science, it's just a tire.