Sponsored by The Tire Rack

[fdiprete]

I just put a nice set of 18 inch 162's on my 2006 325xi with
225/40ZR18 Michelin Pilot Sport A/S Plus Front
255/35ZR18 Michelin Pilot Sport A/S Plus Rear

They look great and the ride is 10x smoother than the rft's that otherwise make a nice car feel like driving in a washing machine without a helmet.

My set of 16's with contintental rft's is at the shop having blizacks put on them for winter.

While driving home on the highway today I changed lanes from center to left at about 70mph in a spirited way. It felt like the car was going to go flying into the air (without the benfit of wings and other aerodynamic components needed for such a maneuver) It felt just scary and unsafe. My old setup handled the same lane change fine.

It was shocking enough for me to pull over to check things out.
Visual inspection was ok and the ride home was fine.

I'm looking for insight into handling issues here,
eg; are these tires slippery as butter on glass?
Is the added hight to an already high suspension really messing things up?

If temp is a factor is was 43 degrees F when my near launch into space occured.

Thanks

[Joeb427]

http://www.tirerack.com/tires/tirete...e.jsp?techid=5

Breaking In Your Tires


Lea esta página en español

Tires are comprised of many layers of rubber, steel and fabric. Due to these different components, your new tires require a break-in period to ensure that they deliver their normal ride quality and maximum performance. As tires are cured, a release lubricant is applied to prevent them from sticking in their mold. Some of the lubricant stays on the surface of your tires, reducing traction until it is worn away. Five hundred miles of easy acceleration, cornering and braking will allow the mold release lubricant to wear off, allowing the other tire components to begin working together. It is also important to note that your old tires probably had very little tread depth remaining when you felt it was time to replace them. As any autocrosser or racer who has tread rubber shaved off of his tires will tell you, low tread depth tires respond quicker."Don't be surprised if your new tires are a little slower to respond (even if you use the exact same tire as before). Their new, full depth brings with it a little more tread squirm until they wear down.

[fdiprete]

Thank you for the info!

I bought the set from a really good guy here
http://www.e90post.com/forums/showthread.php?t=299154

The tires are nearly brand new so you may be correct - I sure hope so.

[Joeb427]

Originally Posted by fdiprete

Thank you for the info!

I bought the set from a really good guy here
http://www.e90post.com/forums/showthread.php?t=299154

The tires are nearly brand new so you may be correct - I sure hope so.

I have the same tires and never had a problem.I like 'em.

[pruettfan]

Every new tire has a coating on them that has to be essentially driven off of them. As stated above break them in. When I first got my Vredestiens they felt very slippery, I knew to expect it so I just took my time and after 20-30 miles I felt that they were ready for spirited driving. Give them a few more miles and they will be fine.

[lonestar22]

shouldnt u not be putting a staggered setup on an AWD car?

[fdiprete]

In short, yes you can put a staggered setup on an xi.
In fact, the 162's are an option with the sports package.

There are many discussions about this topic and the posters that claim not to be able to do this parrot the requirements for a subaru

In the XI area there are many references to understeer (or perhaps in this case oversteer) which I may be encountering. Since it is a new experience for me I may have to adjust my driving accordingly.

I'm hoping to get more info from XI drivers also.

[JaysBlueE92]

oversteer may be part of the issue, but I think it's what others have stated already: a simple case of tire break in.

[D0WNxiSH1FT]

The issue with staggered set ups is the different tire heights cause the center diff (but you don't have one. Don't know the effect on a clutchpack) to constantly work and thus burn out. If you can get the same height it would be ok but that would require measuring. The other thing is staggered works for rwd cus the rears bee the traction and it emphasizes the rwd look. In awd all ties get the same power (ok 40:60) but it looks dumb on awd. I did see the set up stock on a X5 tho. Guess it's safe

[ss134]

Also-check the pressures!!!

[135forthewin]

Check the tire pressure. A buddy had his tires put on at a local shop and they put the pressures way too high and it gave the car a floaty and unsafe feeling.

EDIT: I never learned to read, I guess +1 to the guy above me haha

[LuvMyRide]

Could've been a ton of possibilities... We can sit here and speculate all day long.. we're glad your safe and evrything is seemingly ok..

[fdiprete]

Thanks to all. A lot of great tips. The feeling of leaving the road was quite frightening and I'm not accustom to it.

Take-aways so far:

1) go easy until the tires are sure to be broken in

2) tire pressure - I'm running 32psi. It may be too high - specs anyone?

3) oversteer - Today I hit the throttle on an on-ramp keeping the wheel static to test this. The car changed pitch into the turn and the rear end felt light. The xi usually pulls out of the turn instead of into it. That will take some getting used to...

In a month I'll be putting the snows with 16 inch rims back on which will be a new experience also.

[flip4335]

Originally Posted by fdiprete

Thanks to all. A lot of great tips. The feeling of leaving the road was quite frightening and I'm not accustom to it.

Take-aways so far:

1) go easy until the tires are sure to be broken in

2) tire pressure - I'm running 32psi. It may be too high - specs anyone?

3) oversteer - Today I hit the throttle on an on-ramp keeping the wheel static to test this. The car changed pitch into the turn and the rear end felt light. The xi usually pulls out of the turn instead of into it. That will take some getting used to...

In a month I'll be putting the snows with 16 inch rims back on which will be a new experience also.

My impressions:

1) ditto on tire break-in

2) tire pressure: Check your driver side door sill for proper inflation. On my 335i sedan, the tire pressure called for 39psi fronts/45psi rears if I were to drive up to and over 100mph consistently (hehe...), so for an XI, it might be different.

3) oversteer: You now have 18s instead of 16s, which means the sidewall is much smaller and you don't get the squishiness of a taller sidewall, which might contribute to the oversteer, because you probably reacted as if you still had your 16s on the car. The 18s track much more deliberately. I have the same setup with 162s and they track like rails... I do believe, though, that you were just reacting as if you still had your 16s on your car. You will find the steering response to be more sensitive with 18s...

[fdiprete]

ok - I checked the manual and this setup is listed under the 330xi section.
(mine is a 325xi).

The pressure for 4 people + luggage in the car is 35F and 36R (up to 100mph) with or without sport package. I have them set at 32 all around.

(the 16 inch spec on the door frame is 30/36)

hmmm.

[flip4335]

Originally Posted by fdiprete

In short, yes you can put a staggered setup on an xi.
In fact, the 162's are an option with the sports package.

There are many discussions about this topic and the posters that claim not to be able to do this parrot the requirements for a subaru

In the XI area there are many references to understeer (or perhaps in this case oversteer) which I may be encountering. Since it is a new experience for me I may have to adjust my driving accordingly.

I'm hoping to get more info from XI drivers also.

OBTW, I also drive my wife's Mercedes Benz E350 4Matic Sport Sedan, very similar to a 5-series Xi. That vehicle has 18x8.5 wheels all around for a square setup, running Conti all-seasons. I would have loved a staggered set for her car because of the 40/60 power ratio of the 4Matic. M-B's staggered set is only .5 inch wider in the rears, much like the 162s.

Driving the E350, I notice understeer when I am pushing around a sweeper or corner hard, which transfers the normally 40/60 front/rear power ratio to the rears (up to 0/100 in a 4Matic at times) under hard acceleration, so the rears push forward harder than the fronts could negotiate, creating a sideways slide drift (See Fast & Furious: Tokyo Drift ). Eventually, the rears propel me out of the understeer as I turn the steering wheel into the drift, and I am gone in a jiff when the rear tires bite. I have to ensure that the rears have more tire pressure than the fronts because of the 40/60 power ratio, otherwise, the handling characteristics would be different and uncertain.

I wanted to clarify what someone said earlier about wheel size:

When you plus up your wheels, you automatically change the aspect ratio of your tires to match the wider diameter of the wheels. Going from 16 to 18s is a dramatic 2-inch increase in wheel dimensions. Having said that, the size of the tire changes to accommodate the new wheel size, so the overall dimensions of the entire package (wheel+tire) is roughly the same at 18 inch as it is at 16 inch. Check out Tire Rack and this web site to compare 16 inch wheels and tires to 18s: http://www.miata.net/garage/tirecalc.html

When I had smaller diameter wheels and fatter tires (taller sidewalls), I had to drive a certain way to achieve my goals within the driving characteristics that those tires provided. When I switched to bigger wheels and smaller aspect ratio tires, I didn't have to overpower the steering wheel to compensate for the roll of the old wheels/tires. That takes some getting used to, but adds a whole new chapter in the fun-to-driveometer.

Great choice on your set of 162s. I love them, too. You will definitely like the increased maneuvering characteristics of your new shoes!

[WLS]

Howdy,

I have a 335xi and I run a staggered set-up.

Your problem is most likely tire break-in or if it was wet hydroplane.

A staggered set-up will accentuate understeer NOT oversteer so it is very unlikely that is what you felt.

The staggered set-up is a factory option on the 335 and if you are really curious there is extensive debate in the xi forum, but, it does not hurt the car.

[Dubbedoutbimmer]

Originally Posted by Joeb427

http://www.tirerack.com/tires/tirete...e.jsp?techid=5

Breaking In Your Tires


Lea esta página en español

Tires are comprised of many layers of rubber, steel and fabric. Due to these different components, your new tires require a break-in period to ensure that they deliver their normal ride quality and maximum performance. As tires are cured, a release lubricant is applied to prevent them from sticking in their mold. Some of the lubricant stays on the surface of your tires, reducing traction until it is worn away. Five hundred miles of easy acceleration, cornering and braking will allow the mold release lubricant to wear off, allowing the other tire components to begin working together. It is also important to note that your old tires probably had very little tread depth remaining when you felt it was time to replace them. As any autocrosser or racer who has tread rubber shaved off of his tires will tell you, low tread depth tires respond quicker."Don't be surprised if your new tires are a little slower to respond (even if you use the exact same tire as before). Their new, full depth brings with it a little more tread squirm until they wear down.

this is way different but im old school to and when I had my tires on the ducati replaced I asked if needed to be carefull they said no they no longer use that lubricant....

[Firefly6]

Originally Posted by fdiprete

ok - I checked the manual and this setup is listed under the 330xi section.
(mine is a 325xi).

The pressure for 4 people + luggage in the car is 35F and 36R (up to 100mph) with or without sport package. I have them set at 32 all around.

(the 16 inch spec on the door frame is 30/36)

hmmm.

Maybe someone with an 18" Sport setup can chime in. The pressures could be different depending on the tire. Door jamb settings are usually softer than than whats on the tire by around 4psi front and 2psi rear. You may at least want to take 2psi off the front.

[jgalaxy]

Originally Posted by Firefly6

Maybe someone with an 18" Sport setup can chime in. The pressures could be different depending on the tire. Door jamb settings are usually softer than than whats on the tire by around 4psi front and 2psi rear. You may at least want to take 2psi off the front.

I also run 2psi lower up front on my coupe to help offset a little of the understeer. I have 17 square setup for the track, 18 square and staggered setup for winter and 19" excessively staggered for summer and my car does not exhibit any of the behaviors experienced by the OP.

What you may have experienced was the absolutely poor suspension qualities of the XI. The XI is infamous for its excessively soft suspension which lends itself to poor recovery on compression. I.e. bouncy bouncy effect as the car's weight is transfered from side to side in spirited steering maneuvers or if hitting dips or potholes while cornering.

I have since removed the stock springs/shocks for coilovers and am very pleased with the results.

OP, you may want to ask the question directly on the XI forum and getting some added input.