Tire Sidewall Height.

[mariodr]

Has anyone tried increasing their tire sidewall height on an 07 X3 with a standard 17" rim. The size I have on there now is 235/55R17, which everyone is familiar with. If I was to increase the sidewall height by 1", for a diameter difference of 2", do you think rubbing would occur? Would handling suffer?

[djfitter]

It will totally throw off your speedometer/odometer. Not sure about any other problems. :dunno:

dj

[AzNMpower32]

Someone years ago installed P235/65R17 tyres and it was fine, but there was some minor rubbing.

[innovativeit]

It will totally throw off your speedometer/odometer. Not sure about any other problems. :dunno:

dj
+1
Adding approximately two inches to the overall diameter of the tire will throw off the speedometer/odometer by approximately 7 - 8% as in 70 mph would really be 75 mph.

[AlanLX3]

Wow - so rare to see a sane post on wheel sizes compared to the usual "can I fit 22" ghetto rims with some electrical tape for tires on my X3?" :D

As mentioned about the biggest problem is odometer/speedometer calibration since this will throw the factory settings out the window. The standard 17's do offer a fair amount of sidewall for light off pavement duty which is what the X3 is designed to do - what do you plan to do with yours that requires more? I do take ours out on rough unpaved roads quite often and it does quite well but I have never considered using it for true hard core offroad travel.

[mariodr]

No, I really had not intended any major offroading, just looking to "cushion" the ride a little. It sounds like 235/60R17 may the max then as 65 is rubbing. Do you think an extra half inch would make much of a difference?

Thanks for the advice guys. :thumbup:

[AlanLX3]

Did you get the Sport suspension? I made sure I did not get it in our 2005 and with the standard 17" rubber it's a downright cushy ride on a rough road.

[mariodr]

No, we do not have the sport suspension. My wife still thinks the ride is too rough, even on a good day. For me though, I think the ride is ok. The only big difference I notice is the lack of good accoustic isolation from road imperfections. On my E90, road thumps register as mild noises inside, while in the X3, it registers as a loud thump, especially from the rear axle. The load noise creates the added effect of making the thump seem like more of a bump inside. I hope the next generation X1/X3 feature better noise isolation as is evident in the 3 series cars.

The other complaint I have on the car is the amount of body lean going into corners. For a very tight suspension, which the X3 clearly has, there really should be no body lean at all. On my E90, you can take a turn very sharply, and barely feel the body lean. On the X3, the vehicle noticably dips. I know it has a higher center of gravity, but the engineers should have done a better job. Clearly suspension systems out there can do that, such as witnessed in the Audi Q5.

[AlanLX3]

Definitely a notable lead in the corners compared to an E90 series car. It still corners well for it's height and was a lot better when the suspension was newer so you may find that replacing the shocks helps in the corners. The X3 is lots quieter than the Z4 Coupe I just got rid of but definitely noisier than my new E91.

[vrooom3440]

...The other complaint I have on the car is the amount of body lean going into corners. For a very tight suspension, which the X3 clearly has, there really should be no body lean at all. On my E90, you can take a turn very sharply, and barely feel the body lean. On the X3, the vehicle noticably dips. I know it has a higher center of gravity, but the engineers should have done a better job. Clearly suspension systems out there can do that, such as witnessed in the Audi Q5.

Even German engineers can not change the laws of physics.

Some years ago Lotus was developing computer controlled active suspension. Their setup would read the road surface and move the wheels to accomodate. The computer software could be tuned to make the vehicle respond however they wanted. For example forward pitch upon braking could be not only neutralized but reversed. It was found to be extremely disruptive to drivers as they could not tell what the vehicle was doing. Without that sensory input the driver was unable to tell what the vehicle's limits were so control sufferred.

When you corner in your X3 it transfers weight from the inside tires to the outside tires. This is going to happen whether the car leans or not. It is merely a function of height of the CG above ground, something directly affected by the tall design of X3 and increased ground clearance of X3. When you have spent it all, and there is no more weight on the inside tires, and yet still try to spend more... well you get an overdraft notice with a substantial penalty. And your shiney side will not be so shiney anymore nor will your rubber side be down :yikes:

Body lean is a good thing.

Not to mention that body lean is controlled by stiffer springs and/or stiffer anti-roll bars. Since stiffer anti-roll bars generally affect the suspension feel like stiffer springs, and so many people already complain about the X3s ride quality... well I think the german engineers did a remarkable job of balancing body lean with ride quality as it is.

You just cannot in any way expect a high SUV/SAV like the X3 to be even close to the driving dynamics of a low slung and low profile road car like the E90.

[mariodr]

Even German engineers can not change the laws of physics.

... well I think the german engineers did a remarkable job of balancing body lean with ride quality as it is.

You just cannot in any way expect a high SUV/SAV like the X3 to be even close to the driving dynamics of a low slung and low profile road car like the E90.

I think you make some excellent points, but do not really address the shortcomings of the vehicle relative to the Audi Q5 which sports a much better balance between handling and ride comfort. Essentially dynamically the same vehicles with similar mass and center of gravity.

[ghpup]

+1
Adding approximately two inches to the overall diameter of the tire will throw off the speedometer/odometer by approximately 7 - 8% as in 70 mph would really be 75 mph.

Would it also be appropriate to assume that some of the computer controlled DSC, traction and power transfer between front and back be affected. I can't imaging that there wouldn't be some type of impact, not to mention the likely detrimental change to fuel consumption (heavier corners and a less aerodynmic profile).

[AWBMWM3]

Check out this thread started a couple of years ago. The max tire size is something I've been looking for answers on also. I'm still waiting to wear out the current set, but the next set will definitely either be 235/60-17 or 235/65-17.

http://www.bimmerfest.com/forums/showthread.php?t=275791&highlight=

[AWBMWM3]

Here's some pics of a car running 275/40-19 on the rear and 245/45-19 on the front. Not quite what the OP or myself seem to be looking for, but it gives an idea what fits and how it looks.

http://www.bimmerfest.com/forums/showpost.php?p=3457738&postcount=15

[Krafty04]

+1
Adding approximately two inches to the overall diameter of the tire will throw off the speedometer/odometer by approximately 7 - 8% as in 70 mph would really be 75 mph.

Have you checked your speedometer lately against a GPS unit? Our speedometers are almost 5mph off at 70mph, so bumping the tire size up would put it closer to actual.