Michelin tire issue

[JohnnyFry]

I recently replaced my Michelin Defender tires with the newer line Michelin Agillis
tires on my 2008C210P and have noted an interesting issue. Pressure increase on the Defender tires (rear) was typically about 8 PSI running 60MPG in moderate (70°-80° ambient) temperatures. The new Agillis tires seem to have a higher 12-14 PSI rise under the same conditions and similar loading.

Has anyone else noticed the phenomenon? ...or am I imagining things?

[Davydd]

I’ve got constant visual monitoring on my dash with Doran TPMS. I haven’t noticed any significant difference. I am comparing a 2500 Sprinter chassis to a 3500 chassis so not on the same van.

[booster]

We went from MS2s to Agilis (size 265-75-16) on our 07 C190P Roadtrek and we see similar temp rise and pressure increase based on the Tire Minder TPMS for pressure and an infrared thermometer for temps.

[markopolo]

Originally Posted by booster

We went from MS2s to Agilis (size 265-75-16) on our 07 C190P Roadtrek and we see similar temp rise and pressure increase based on the Tire Minder TPMS for pressure and an infrared thermometer for temps.

Similar between the MS2s & Agilis or similar to Johnny's?

I've read that more than 10% pressure increase due to tire temperature rise can be a sign of a problem. A 12PSI increase on the rear tires would 15%.

[SteveWolf]

The question asked is, "Does a fourteen pound tire pressure increase over suggested pressure when driving on a Michelin Agilis affect the safety of that tire?"

That will invoke all kinds of anecdotal opinions. "My neighbor's grandfather says ...." Let's add:

"What study provided the data for the conclusion in question one and where can we get it?" Anyone know anyone at Michelin?

If this devolved in another "automatically change your tires every [2,4,6,8,10,15,20] years" discussion it won't be of value. It will give newbies another rabbit hole to disappear down as they stare at the tire monitor screens.

[booster]

Originally Posted by markopolo

Similar between the MS2s & Agilis or similar to Johnny's?

I've read that more than 10% pressure increase due to tire temperature rise can be a sign of a problem. Johnny didn't specify front or rear but if fronts for example a 12 to 14 psi change could be 20% psi increase. 15% if that increase is on the rear tires.

Similar between the MS2s and Agilis on our van.

[markopolo]

Thanks Booster. I figured that but just wanted to be sure.

I've noticed up to a 7 psi increase on the rear tires going from ambient to tire heating up from driving. Less than 10% psi increase.

A 12 to 14 psi increase is worth investigating further. Michelin's 2 psi per 10 degree F above 65F increase "rule of thumb" indicates that 14 psi would be the result of 70F increasing to 140F.

[GroupB]

Was anything else changed or adjusted during the tire change? Emergency brake dragging comes to mind.

[booster]

Originally Posted by markopolo

Thanks Booster. I figured that but just wanted to be sure.

I've noticed up to a 7 psi increase on the rear tires going from ambient to tire heating up from driving. Less than 10% psi increase.

A 12 to 14 psi increase is worth investigating further. Michelin's 2 psi per 10 degree F above 65F increase "rule of thumb" indicates that 14 psi would be the result of 70F increasing to 140F.

The 2 psi per 10*F is pretty close to the amount on the rear at 80psi. I don't recall the exact calc conversion but it is a bit less. I use 2psi for the back. Since it is a % change the front is less because of the 60-65psi range and there I use 1.5* which is also just close but good enough.


On the rear of a Roadtrek we found our rear tires got very hot compared to the fronts even on our 07 C190P when we had the original semi floating axle in it, and I would guess that a 210 would be even worse as it has the higher rear weight if it also has the semi floating Dana Super 60 rear axle in it. Heat from the axle bearings is very high in those axles and the aluminum wheels especially seem to transfer the heat to the tires. There is a thread on the forum someplace that has the actual numbers for it, but it was a long time ago so would have to dig for it.


This would not, of course, explain the difference between the Defenders and the Agilis the OP saw if it happened overnight when the tire change was made.


Marko, do you have Agilis on your van now?

[markopolo]

I still have the LTX/M/S2 tires on the van. Here's a link about wheel offset issues and the replacement rims you installed:

https://www.classbforum.com/forums/f...hevy-1985.html

It seems that the correct offset rims & new tires resulted in a big improvement even before the axle swap.

Originally Posted by booster

...................... The wheel hubs, both front and rear, run substantially cooler. It was near 90* when we came home today, and you could lay your hand on the hubs/wheels comfortably. In the past they would get too hot to stay on them. I assume this is because of the reduced strain on the wheel bearings.

Rear tires went up about 6 psi, fronts about 4 psi after two hours at 55 mph and 90* weather.

The van feels much more car-like with stock offset, compared to the original aluminum wheels.

The mystery on this topic as Booster points out is why the large temperature/psi increase is just showing up on Johnny's van now after getting new tires.

[booster]

Originally Posted by markopolo

I still have the LTX/M/S2 tires on the van. Here's a link about wheel offset issues and the replacement rims you installed:

https://www.classbforum.com/forums/f...hevy-1985.html

It seems that the correct offset rims & new tires resulted in a big improvement even before the axle swap.

The mystery on this topic as Booster points out is why the large temperature/psi increase is just showing up on Johnny's van now after getting new tires.

I don't recall if I did a full check of the actual hub temps before and after the new wheels back then, but I wish I did and had a log of it. As you mention all of the things probably made a difference, bigger tires, correct offset, wheels not aluminum so not as conductive (steel wheels). We see closer to 10 psi in the rear if it is very hot out and the tires were set on lower side of normal before we left, but we drive very much faster now for most part, including running steady 72+ in 103*F across Utah a few years ago. Pavement temp makes a big difference so black asphalt worse than concrete by a noticeable amount.

I think it was Photog that had some very high pressure increases in his 190 that he had mentioned, primarily in the rear, back in that same time period.

Johnny has new tires, so maybe they just need so break in to flex with less heat generated, as they are touted as being firmer sidewalls. Ours got a better handling feel to them over the first few hundred miles, and after a long hot day running fast they were noticeably better the next day and steady since.

I think some checking with an infrared temp gun would tell a lot. Check front and rear tire and hub temps, front and rear, both sides of the van to see where they are. We have often seen 10* hotter on the sunny side of the van if the sun is hot that day.


I just went back to me last Agilis post on my discussion about our new tires. For reference, measured with the infrared, our Agilis ran between 110-120*F on a 93* day running in the 70mph range.

[JohnnyFry]

I always carried an IR gun in my days towing a fiver, guess I will be carrying it again and logging some temps.