Wrong way tires?

Dumb question - 

On the racetrack, in the dry, is there a good reason not to run my rear "directional" tires in the wrong orientation?  i.e. rolling in the opposite direction than what was intended?

Reason I ask, I just put on a new set of tires, did one track weekend and forgot to rotate them(front to back) after the first day, and let someone else drive the second day.  I don't think they were as diligent as they should have been on tire pressure, and the driver front developed some decent outer edge wear.  There is some slight outer edge wear on the driver rear, but it's really not bad.  

Long story short, Is it a big deal to swap front to back, then swap the rears(formerly fronts) side to side so the more edgeworn tire ends up on the passenger rear?  My local tire shop(which I use to mount tires ~10x/yr - at least used to- never again)  won't re-mount the tires for me on opposing rims in order to move the worn part to the inside of the rim and have it roll in the correct direction...

I have an event coming up this weekend, don't have time to get 2 matching tires shipped and mounted in time...

What would you do?

nexen sur4 200tw street tires...

In dry conditions, I don't know that it makes any real difference at all, seeing as the grooves in a tire are there to evacuate water efficiently (hence directional). 

Well, tires can be both directional and assymetrical, so there could be some effect even in the dry in that case. But, for rear tires especially i would say it's a valid thing to try. If they're not assymetrical i see even less reason not to try it. 

Way back when I ran Toyo RA1's, Toyo told me that in the dry it didn't matter what direction you ran them.  Once all the "directional" tread was gone I ran them whichever way was best for the maximizing tread wear at the event.

It'll probably work just fine.

Even in the rain it does not matter all that much until you get to incipient hydroplaning.

Asymmetrical tires, on the other hand, do NOT like being run inside out...

Knurled. said:

Even in the rain it does not matter all that much until you get to incipient hydroplaning.

That happens sooner than you think. I’ve had a car snap sideways on me on the interstate in the rain, and it was nowhere near when I would have expected hydroplaning. Turns out it had one rear tire on backwards. Very exciting. Those tread blocks do more than you might expect. 

Thanks everyone for putting my mind at ease.  I don't believe they are Asymmetrical, (other than the wear) but i will double check.

I think they'd probably last the entire event regardless, it's just a time trial with only four 15min. sessions for the whole weekend. Obviously I'd much prefer to make them last as long as possible though...

I used to do it all the time. No troubles at all.

Also, it is very, very rare to have an asymmetric and directional tire, because you would have different part numbers left and right.

Streetwiseguy said:

I used to do it all the time. No troubles at all.

Also, it is very, very rare to have an asymmetric and directional tire, because you would have different part numbers left and right.

Corvette did this for years (Eagle GS-C was asymmetric and directional).  IIRC the NSX did too, having four different part numbers.

So, not necessarily uncommon.  I don't remember if Corvettes had staggered sizing during the GS-C years.

Knurled. said:

Streetwiseguy said:

I used to do it all the time. No troubles at all.

Also, it is very, very rare to have an asymmetric and directional tire, because you would have different part numbers left and right.

Corvette did this for years (Eagle GS-C was asymmetric and directional).  IIRC the NSX did too, having four different part numbers.

 

So, not necessarily uncommon.  I don't remember if Corvettes had staggered sizing during the GS-C years.

So, pretty rare then...

In reply to Streetwiseguy :

That depends on your perspective.  I remember every fifth car being a C4 'vette for a while.

On the other hand, I used to think Evos were frickin' rare cars, and I started a new job 30 minutes in a different direction and I regularly see several Xs and even a couple IXs on the road.  No more Maseratis though.  (Wow the Maserati SUV is fugly, I thought they were Hyundais at first)

I swap my directional  so the worn outsides become the insides every year (autocross) The tires still rotate  the correct  direction. I have my own tire machine so there is no explaining on how to do it.

pjbgravely said:

I swap my directional  so the worn outsides become the insides every year (autocross) The tires still rotate  the correct  direction. I have my own tire machine so there is no explaining on how to do it.

I bought the Northern tool manual tire changer to try to do exactly this.  So far limited success practicing on old rims...  easy enough to get off, but hard to get re mounted...

A lot of drifters run directional Federals backwards to avoid severe chunking. It's worth a shot if it's a directional non-asymmetric tire.

We've done this time of times in champcar endurance races.  Rain is the only issue.  

Other than that, go for it.

Also, the outside wear comment is concerning me slightly.

I would get a tire pyrometer and see what the tire wants.  Excess air pressure is a bandaid.  Those tires probably want more camber.

wvumtnbkr said:

We've done this time of times in champcar endurance races.  Rain is the only issue.  

 

Other than that, go for it.

 

Also, the outside wear comment is concerning me slightly.

 

I would get a tire pyrometer and see what the tire wants.  Excess air pressure is a bandaid.  Those tires probably want more camber.

Agreed, but I am at the limits of the factory adjustment (~-2deg,) and I want to keep this car eligible for the scca "sport" time trial class. (mazda RX-8 S5) so there really isn't much i can do about it... 

Can you add caster?  That would help too!

In reply to wvumtnbkr :

99% sure caster is fixed, but I could be wrong...  I'll definitely check!  Thanks

cbaclawski said:

pjbgravely said:

I swap my directional  so the worn outsides become the insides every year (autocross) The tires still rotate  the correct  direction. I have my own tire machine so there is no explaining on how to do it.

I bought the Northern tool manual tire changer to try to do exactly this.  So far limited success practicing on old rims...  easy enough to get off, but hard to get re mounted...

It takes practice to get the tires on. I had to watch a few videos and used a block of wood to hold the bead into the groove on stiffer tires. A real machine is a joy to use after the manual changer.

What about asymmetrical but not directional? How different can they be?

pjbgravely said:

cbaclawski said:

pjbgravely said:

I swap my directional  so the worn outsides become the insides every year (autocross) The tires still rotate  the correct  direction. I have my own tire machine so there is no explaining on how to do it.

I bought the Northern tool manual tire changer to try to do exactly this.  So far limited success practicing on old rims...  easy enough to get off, but hard to get re mounted...

It takes practice to get the tires on. I had to watch a few videos and used a block of wood to hold the bead into the groove on stiffer tires. A real machine is a joy to use after the manual changer.

Finally got it on there by using ratchet straps to tie and compress the tire against the rim below the "shelf".  Took one in the back, and two on the sides, but made it doable...

white_fly said:

What about asymmetrical but not directional? How different can they be?

There are some tires where it's just the tread pattern that's asymmetrical, and you can run those inside out without too much issue.

There have also been a few where the sidewall construction is asymmetrical, which is more significant.

I've run mine backwards on track.  When it's dry, no problem, as others have mentioned.  When wet (random freak storm that lasted 15 min just as I got on track...), they didn't start to hydroplane until around 40mph, which was surprising.  I was pretty easy one it obv, but still, I would've thought it'll start to veer at 20mph.  

Some tires have a band of harder rubber on the side that is supposed to be the outside but have a non-directional tread. 

Years ago I read that for directional tires the direction they turn only matters in the rain for water channeling purposes.  In the dry, the article said, it did not matter.

Of course, now-a-days, we have tires available that are both directional and have to be mounted with the outside facing outside.