Service AWD

[manicrodder]

Put new Sumitomo’s on the 300 two weeks ago and noticed yesterday an 8 penny nail stuck in the sidewall just past the tread and it was perpendicular to the concrete. Of course it had to be replaced(glad I got road hazard).
Put the doughnut on and the “Service AWD” came on and then went off and never reappeared. I assumed from the different wheel diameter?

 

[Lubener]

With AWD, all four tires need to be exact in dimension. Your statement is correct regarding the wheel diammeter. I would not drive for any length of time with a donut spare for fear of damage occuring with AWD. Still wondering how a nail could have positioned itself as you describe.

 

[PimTac]

Sounds like someone nailed your tire.

 

[Kira]

What might be cool and useful is a list of AWD systems based on their ability to forgive mismatched wheel diameters.

Ex: I've read a bunch about Volvo V70 cars as I've owned 3 of them. The AWD system used in 850 and P1 chassis vehicles (Getrag) indeed had the "4 matched wheels" requirement. The Haledex system used in later P2 cars was said to be forgiving.
How much so was never mentioned.

Another thing never mentioned BY ANYBODY was employment of 5 wheel tire rotations such that you could lose a tire in a well worn set and still have 4 good, matched tires. It'd be cheap insurance.

 

[edyvw]

Your donut should be same diameter. How was pressure in it? Usually people don’t check spare tire pressure.

 

[manicrodder]

Pressure is good but spare doesn’t match the 19” wheel.

 

[bdcardinal]

Check your owners manual about where to put the spare. I seem to remember when I had my Volvo S60R they said to put the spare on the rear to minimize impact to the AWD system.

 

[CKN]

Your donut should be same diameter. How was pressure in it? Usually people don’t check spare tire pressure.

No-those things are not necessarily the same size.

 

[manicrodder]

Check your owners manual about where to put the spare. I seem to remember when I had my Volvo S60R they said to put the spare on the rear to minimize impact to the AWD system.

It is on the rear.

 

[Astro14]

What might be cool and useful is a list of AWD systems based on their ability to forgive mismatched wheel diameters.

Ex: I've read a bunch about Volvo V70 cars as I've owned 3 of them. The AWD system used in 850 and P1 chassis vehicles (Getrag) indeed had the "4 matched wheels" requirement. The Haledex system used in later P2 cars was said to be forgiving.
How much so was never mentioned.

Another thing never mentioned BY ANYBODY was employment of 5 wheel tire rotations such that you could lose a tire in a well worn set and still have 4 good, matched tires. It'd be cheap insurance.

I think because the spare on those Volvo AWD cars is a donut.

It’s only a full size on the FWD, and even then, it’s a steel wheel, with a 16” tire, which looks pretty dumb next to the three other 17” alloys...

 

[manicrodder]

Sounds like someone nailed your tire.

I thought this in the beginning. However it was out about 3/4 of an inch and was flush with the tread on the tire.

 

[UG_Passat]

Pressure is good but spare doesn’t match the 19” wheel.

135/90r17 spare tire, 8.9% smaller than 235/55r19 that's Chrysler engineering for you

 

[JTK]

Donut or not, the overall diameter should be close, if not right on with the OEM tire size, especially on a true AWD vehicle.

Interesting how your 300 "knew" it had the spare on. I'm wondering if it has anything to do with the lack of TMPS sensor in the spare.

 

[UG_Passat]

Donut or not, the overall diameter should be close, if not right on with the OEM tire size, especially on a true AWD vehicle.

Interesting how your 300 "knew" it had the spare on. I'm wondering if it has anything to do with the lack of TMPS sensor in the spare.

In the case of the 300, it's not even close. It knows because the wheel speed sensor is showing a significant difference on the spare tire.

 

[JTK]

In the case of the 300, it's not even close. It knows because the wheel speed sensor is showing a significant difference on the spare tire.

Man that's interesting.

That's how the vehicle knows to set the message/code and disable the AWD then. Because of the wheel speed consistently being different from the other 3.

 

[Nick1994]

Sounds normal to me. Every time we'd have to use the spare donut on my mom's 03' Buick Rendezvous AWD the AWD would disable itself immediately. It knew.

 

[edyvw]

No-those things are not necessarily the same size.

They should be. Tells a lot about manufacturer.

 

[CKN]

They should be. Tells a lot about manufacturer.

I have a spare OEM tire on my SIlverado. While not a "donut" it also is not the same size as the other tires. A lot of manufacturers do this.

 

[manicrodder]

Donut or not, the overall diameter should be close, if not right on with the OEM tire size, especially on a true AWD vehicle.

Interesting how your 300 "knew" it had the spare on. I'm wondering if it has anything to do with the lack of TMPS sensor in the spare.

Don't know.

 

[IcarusLSC]

Huh, interesting. I'll have to check my spare in my 300 to see if its the same diameter as the rest of the tires...