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Old 05-26-2016, 07:23 AM   #43
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Originally Posted by Mr. B View Post
Now, following Protagonist's math:

Rear - 6,510 lb : 4 wheels : 32 sq. in. = 50
I calculate 50.8 which rounds up to 51psi for the rear to keep the same contact area between tire and ground. Going any lower will cause additional sidewall flex and raise the tire temperature, increasing the possibility of a blowout.
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Old 05-26-2016, 12:11 PM   #44
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Or the camber is too positive which is usually the case unless the AI has been aligned since it left the factory. After reading how a lot of folks were experiencing outer edge wear and noticing the same thing, I had the front end aligned and rotated the tires/wheels. Front tire wear is now uniform. YMMV

My theory is that the extra weight added to the rear causes the front to raise slightly which would increase positive camber.

I had my front realigned about 40,000 miles ago when I was getting more wear on the outer edges of front tires. I got new Michelins then. Now the wear is on both inner and outer edges with more wear on inner edges. Likely the pressure at 55 psi is a bit low for proper tire wear on front tires.


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Old 05-26-2016, 10:16 PM   #45
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Mr B, the chart you attached is for XPS RIB tires, and they are probably not recommended for the rear axle on a Sprinter since they are extra heavy duty and probably won't make the rear ride softer under any circumstances. Also the tire dimensions are non-standard: should be 215.85 x 16 I believe.
Incidentally, that chart shows the total rear axle weight, no dividing by 4 is necessary here.


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Yes, UK Dude, I was mistaken with the tires size - we all have originally equipped 215x85x16 of course, and there are no RIB but regular traction tires, though the tire pressure chart shows the same numbers for all in this size.

The following is the result of my deep researches and conversations in different American and Russian forums.

Below is a screenshot from the official Michelin chart for the load and pressure.
The load is indicated per axle, not per wheel.

As I've told before, my real weight is 3520 lbs on the front axle, and 6510 lbs on the rear axle.

As per the chart, pressure have to be following:
For my front axle it is recommended 45 PSI in each tire.
For the rear axle it is recommended 45 PSI in each tire.

In accordance with official Michelin recommendation, from now and on I will be safely keeping the tire pressure of 45 PSI in each of four rear tires.

In accordance with our Protagonist recommendation, from now and on I will be safely keeping the tire pressure of 51 PSI in each of two front tires.

Bingo, Gentelmen!
Comments are appreciated!
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Old 05-27-2016, 05:29 AM   #46
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In accordance with our Protagonist recommendation, from now and on I will be safely keeping the tire pressure of 51 PSI in each of two front tires.
Each REAR tire, not each front tire. You misread my post.
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Old 05-27-2016, 11:53 AM   #47
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Each REAR tire, not each front tire. You misread my post.
Did you see the Michelin table I've attached?
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Old 05-27-2016, 12:00 PM   #48
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Did you see the Michelin table I've attached?
Yes I did.

But if you're going to say, "In accordance with our Protagonist's recommendation…" you need to actually use my recommendation rather than misusing it. Don't use my rear tire recommendation for your front tires.

If you want to go by the Michelin table exclusively for all six tires, that's fine by me. I'm just opposed to being misquoted.

Oh, and maintain your spare at the highest pressure you use for any tire on the ground. It's a lot easier to bleed out air from the spare to match the tire you're replacing than to pump it up to match.
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Old 05-27-2016, 12:27 PM   #49
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Yes sure )
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Old 06-11-2016, 11:00 AM   #50
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Originally Posted by 73shark View Post
Or the camber is too positive which is usually the case unless the AI has been aligned since it left the factory. After reading how a lot of folks were experiencing outer edge wear and noticing the same thing, I had the front end aligned and rotated the tires/wheels. Front tire wear is now uniform. YMMV

My theory is that the extra weight added to the rear causes the front to raise slightly which would increase positive camber.
I had that camber and alignment "fix" done at 5,000 miles. Unfortunately, I did not pay attention to tire wear at that point. Today at 14,500 miles, I notice the front tires are WAY WORN on outer edges ... shockingly so.

How often should we be aligning? Did I run through too many potholes or something? At this point I'm almost thinking about replacing the front tires, but don't want the same thing to happen again.
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Old 06-11-2016, 11:23 AM   #51
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...SORRY, meant extremely worn on INSIDE edges of both front tires
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Old 07-14-2016, 11:06 PM   #52
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Report: Have a pleasure to ride few recent round trips Florida-NY with front tires pressure of 56, and 46 is each rear.
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