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[Lute__]

I have my M3 stored for the winter. Unfortunately I have it stored outside in a private parking lot (concrete floor) with a car cover and battery tender attached. Now I am concerned about tire flat spotting. All the info out there says permanent tire flat spotting doesn’t really happen with modern radials, and that it is more of an issue with older bias ply tires. I have brand new Michelin PSS on the car, that I have inflated to 40 psi.

My question is do I need to worry about this? My car will remain parked until about March-April. Should I roll the car forward and back periodically or is that unnecessary? Inflate tires more than 40psi? Any comments are appreciated.

[LarThaL]

I am storing for the winter also. I am inflated to 40 psi also. I plan to roll it a little every few weeks.

[slipaway37]

Originally Posted by Corbis

I have my M3 stored for the winter. Unfortunately I have it stored outside in a private parking lot (concrete floor) with a car cover and battery tender attached. Now I am concerned about tire flat spotting. All the info out there says permanent tire flat spotting doesn’t really happen with modern radials, and that it is more of an issue with older bias ply tires. I have brand new Michelin PSS on the car, that I have inflated to 40 psi.

My question is do I need to worry about this? My car will remain parked until about March-April. Should I roll the car forward and back periodically or is that unnecessary? Inflate tires more than 40psi? Any comments are appreciated.

I ALWAYS kept my stored vehicles off-floor by use of jack stands. I also used a fuel stabilizer, but yours won't be stored all that long.

[Lute__]

Originally Posted by LarThaL

I am storing for the winter also. I am inflated to 40 psi also. I plan to roll it a little evey few weeks.

I think this probably my safest bet. It's just a pain to have to slip the cover off, adjust the battery tender etc.

[Lute__]

Originally Posted by slipaway37

I ALWAYS kept my stored vehicles off-floor by use of jack stands. I also used a fuel stabilizer, but yours won't be stored all that long.

Yep full tank with stablizer in there. The vehicle could be stored longer so I didn't want to take a chance. Jacking the car up is not an option for me, besides, there are suspension issues (sagging springs etc) to deal with when putting the car up on stands. If it's a choice between the tires or suspension getting comprimised I'd rather the tires.

[Lute__]

So is there any consensus on whether modern radial tires flat spot when sitting for extended periods?

[anselmw]

Originally Posted by Corbis

So is there any consensus on whether modern radial tires flat spot when sitting for extended periods?

I have not really seen modern radials permanently flat spot. I have been parking my M coupe for the winter and have never had any issues with flatspotting. Now if you are storing for longer than the winter, maybe.

Option would be to use the tire cradles if you are really worried about it.

[05Mdriver]

Originally Posted by LarThaL

I am storing for the winter also. I am inflated to 40 psi also. I plan to roll it a little evey few weeks.

I also did / do this.

[SenorFunkyPants]

Originally Posted by LarThaL

I am storing for the winter also. I am inflated to 40 psi also. I plan to roll it a little evey few weeks.

This

[GreenLantern]

I've always inflated higher (i.e., to 40 psi), and have been fine. Never had to roll a little every few weeks, never had to worry about putting it up on stands (word has it this hurts your suspension, anyway). I know lots of collectors who also don't fret too much about flat spots, and never seem to get any.

Are flat spots a myth? No. Are they as serious of an issue with modern tires (these days) as people seem to claim? Not in my opinion.

*shrug*

[ben@tirerack]

Originally Posted by Corbis

So is there any consensus on whether modern radial tires flat spot when sitting for extended periods?

Radial tires definitely can flat spot when sitting for extended periods. It is not usually permanent, but I have seen it happen.

Adding air pressure is good. Parking on something with some give is good. Some guys swear by tire cradles.

The absolute best (and of course least convenient) is putting the car on jackstands. As noted above, don't just leave the suspension dangling, put some kind of blocks under the wheels.

In most cases you'll be fine with some minor precautions like adding air.

If you do get a thumpy, vibrating feel when you first start out after getting the car out, don't assume the worst. Drive long enough to get your tires up to temperature and see if it goes away. Often the tires just take temporary set, and once they're warmed up they go back to round.

[Lute__]

Originally Posted by ben@tirerack

Radial tires definitely can flat spot when sitting for extended periods. It is not usually permanent, but I have seen it happen.

Adding air pressure is good. Parking on something with some give is good. Some guys swear by tire cradles.

The absolute best (and of course least convenient) is putting the car on jackstands. As noted above, don't just leave the suspension dangling, put some kind of blocks under the wheels.

In most cases you'll be fine with some minor precautions like adding air.

If you do get a thumpy, vibrating feel when you first start out after getting the car out, don't assume the worst. Drive long enough to get your tires up to temperature and see if it goes away. Often the tires just take temporary set, and once they're warmed up they go back to round.

Thanks for the info.

[PrimeBMW]

Race ramps sells tire cradles specifically for this situation.

[Lute__]

Originally Posted by PrimeBMW

Race ramps sells tire cradles specifically for this situation.

Not feeling spending $275 for those, I am just going to roll it back and forth, every month or so.

[Krockit1]

I've stored cars over the Wisconsin winter for 10 years now and only thing I do for the tires is inflate to 50 psi. I used to roll the car a bit each month but it never changed the results so I don't bother rolling anymore. Tires will be noticeably lumpy in spring (the flat spot does form) but your first drive will take care of it.... the run should be long enough to heat up the whole drive train completely. I do at least 50 mi. Throw in plenty of twisties and you will get the tires hot enough to take out the flat spot. Then you are good to go. A great excuse to drive it like hell- hey you have been waiting all winter! I've run Bridgestone Pole Position exclusively over that time.

[smmmurf]

I did 2 hours on the track on slicks that were 5 years old and sitting on a car for 2-3 years without being rolled... car was fine, no vibrations and a reasonable amount of grip after a few minutes once heat got into them.

On street cars: My PSS don't flat spot after a couple weeks but my Conti DWS flat spot after a couple days of no driving... YMMV