JohnAlderfer1

My 2012 E 350 currently has 40,000 miles on original tires. This car is used only for monthly interstate trips of 700 miles. Amazingly there is a good amount of tread left but I am wondering how far to push it. Car is stored inside and there is no cracking.

homeofstone

Have your tires' tread depths measured at a tire dealer or purchase a tread depth gauge. When you get to about 3/32 of an inch then its time to think about getting tires. If a tire is worn badly on one side or in the middle to 2/32 of and inch or less then it should be replaced.

Arrie

I personally have a low tread depth limit at 3/32". This already is on low side when driving in heavy rain. It cuts the speed way down during southern "down pours".

VegasE

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All tires have "wear bars" in the tread so that when the bars are level with the tread that means the tread is down to 2/32 and must be replaced. However, tire performance suffers as tread wears, so many replace their tires sooner. Performance issues include wet traction, cornering, etc. Personally, it is obvious to me as I drive when tires need replaced because of loss of grip when wet or cornering and this is well before the 2/32 limit.

Note that some tires have wear bars at different depths to let you know how much tread you have just by looking at the tire. For example, the Continental ContiExtreme DWS shows an "S" wear bar pattern indicating the tire is no longer advised for snow, "W' for rain, and the "D" is at 2/32.

Now about age. Most tire manufacturers, auto manufacturers, and Consumer Reports recommend changing tires irrespective of wear after 6 years. Some tire salesmen will tell you sooner, but they are selling tires. The 6 years starts from the "in service" date which is when the tire was mounted on a rim (about the build date for a car that was purchased new - not the purchase date) - even if not in use (like your spare). The caveat to the 6 year limit is heat exposure. If you live in Las vegas like me or run your tires consistently underinflated then cracking will begin sooner. Also note that some high performance summer tires will crack if exposed to below freezing temps even when sitting in a garage during the winter and not in use. Some tires, like folded compact spares that have to be blown p for use, have a shorter shelf life as specified by the manufacturer. I've seen some spares that say their useful life is 4 years.

thenew3

I believe tire rack did a test one time that found 4/32" was the minimum safe tread depth for wet weather use. Anything less would provide almost no resistance against hydroplaning.

Sean1234

My understanding is that after 5 years or so the tires are starting to lose grip in the rubber no matter how much tread is left. The way I look at it is if you are going to get rid of the car in the next year or so I would leave it. But if you are going to keep for another 3 or 4 years I would get the new ones now so that you enjoy newer tires while you have the car. No dealer is going to give you any extra for a trade because the car has new tires.

aeroconfigs

I did mine at 40 and then again at 50 because I didn't like the new ones I put on at 40. Definitely check the depth, if they're below a certain specified limit the tire manufacturer must give you back a portion of the cost that is prorated based on the stated life of the tires. I've found that they don't always make that limit.

Also rotate about every 5k, that should help to avoid uneven wear patterns.

Arrie

Replying to my own post here:


I have put 11500 miles on my Nokian ZLine tires. I have 7/32" tread depth left. Tires started at 10/32".


I will use them until 3/32" depth so I have 4/32" to wear. This should give them about 27000 total miles, which is not bad for this high performance tire.


Will know the wear more accurately when more miles accumulate...