1st mod wheels or ECU tune

[JCL]

Originally Posted by TerminatorX5

I believe there is a hyperbolic relation on the wheel/tire combos - you would not want to put 14" rims on the X (well, 14" will not fit anyways, just for the sake of argument i exaggerated), nor you want to put a 36" rim... there is a sweet spot and the 22" fall at the upper limit of that sweet spot..

which should improve the handling, just as 20" factory rims improve handling on otherwise 17" wheels...

The vehicle was designed for 17". BMW even worked with Michelin to design a tire to optimize that tire size on the X5.

18" tires can improve turn in and steering response. I would suggest that is the sweet spot. Anything bigger than 18" is for fashion IMO. Nothing wrong with that, but let's not use the oft-repeated claim of improved handling as a justification.

It is easy to find many posts about premature rear tire wear, uneven rear tire wear, prematurely worn suspension components, etc. Those problems are all driven largely by overspec'd tire sizes. People don't seem to see the connection, which surprises me.

[conedoctor]

Keep in mind the biggest R compound tire is a 19", if 22's worked better Hoosier would make them

The ECU does not know or care what wheels/tires you put on, My choice is for the 20's for looks, ease of finding tires and will still provide decent economy. The 22's may feel very heavy and hurt at the pump.

[bdubz]

Originally Posted by conedoctor

Keep in mind the biggest R compound tire is a 19", if 22's worked better Hoosier would make them

The ECU does not know or care what wheels/tires you put on, My choice is for the 20's for looks, ease of finding tires and will still provide decent economy. The 22's may feel very heavy and hurt at the pump.

Thx for the input conedoctor. Are you driving on 20's now?

[conedoctor]

The second spring arrives I will be getting some.

If the tire fits the wheel and the contact patch is bigger ultimate grip will be higher but with a huge wheel/tire it will feel lazy and your braking will suffer, now by suffer by the numbers the heavier wheel is harder to stop and start but how much in the real world I don't know and I don't think it much.

Wheel diameter has nothing to do with handling, wheel width and tire size do, so I don't agree that a bigger wheel will handle better. The correct tire on the correct wheel will improve handling but may come at the cost of feel.

I would not say you need bigger brakes for the bigger wheels, good pads maybe but if even then I would think most guys can still lock up their 20's with stock pads and unless your going to road or lap you will not need bigger brakes, that being said you will still out brake every jacked truck with 22's and mud tires with tiny stock brakes lol

Go with 20's and be happy knowing you will save fuel, have more and cheaper tire choices and can get a nice set of replica 20's for $799 all day long.

[TerminatorX5]

This is from wikipedia and thus is NOT the ultimate answer - just something to take into consideration...

Plus sizing is the practice of replacing an automotive wheel with one of a larger diameter fitted with a new tire of lower aspect ratio so that the new tire has the same diameter and circumference as the original tire to prevent any changes in speedometer accuracy, torque and traction control, while reducing sidewall flex and--generally--increasing cornerning ability.
The number following the "plus" describes the number of inches which is added to the diameter of the rim. For example, plus one sizing means increasing the wheel by one inch--from a 15" to a 16" for example.
A 'plus zero' upgrade means changing to a wider tire size while using the same diameter wheel.
Changing to a wider tire requires reducing the aspect ratio (the second number in the sequence of numbers that describes the tire's size). Since the aspect ratio is a percentage which is used to calculate the height of the tire's sidewall, if follows that if a larger number is used for the width, a smaller number must be substituted if the final result is to remain the same—which is the objective of Plus sizing.
Contents [hide]
1 Plus sizing example
2 Advantages
3 Disadvantages
4 Controversial issues
5 See also
6 External links
Plus sizing example[edit]

Original tire Plus zero Plus one Plus two
185/65R15 195/65R15 205/60R16 215/45R17
These are simply examples and do not represent all of the possible combinations which could achieve the same result. For an R16 tire, 205/60, 225/55, 245/50 and 275/45 width/aspect ratio tires have essentially the same diameter.
It is important to remember that actual dimensions of tires in the same size might differ slightly depending on tire brand, model, etc.
Advantages[edit]

Larger tires improve handling and cornering, due to wider tread faces and stiffer sidewalls. Wider tires may decrease braking distances on dry pavement.
Larger wheels with lower profile tires are sometimes aesthetically or culturally desirable.
Disadvantages[edit]

Larger wheels typically cost more. Wider tires tend to be more expensive because they are less common, and there is less competition between brands.
Performance improvements beyond what is achieved in a Plus One sizing are minimal.
Lower profile tires tend to have stiffer sidewalls, which might decrease riding comfort.
During winter, wider tires perform worse. Narrower tires exert more pressure on the contact patch[citation needed], maintaining better road contact through snow.
Larger and wider wheels decreases fuel efficiency and increases consumption. A larger tire footprint can increase the time taken for "return to center" (steering) after taking a sharp turn.
Controversial issues[edit]


This article contains weasel words: vague phrasing that often accompanies biased or unverifiable information. Such statements should be clarified or removed. (July 2009)
Some people claim larger wheels wear faster. Wheels with reduced sidewall heights may increase risk of damaged rims, breaking the bead, and/or damaged sidewalls. The increased width of the contact patch of wider tires may increase the risk of hydroplaning.
Plus sizing tires may enhance the vehicle's value, but altering the vehicle from the factory specifications may reduce value.
The additional height and weight of plus sized wheels may increase vulnerability to rollovers, particularly by changing the center of gravity. During rapid tire deflation at speed, reduced sidewall height may encourage rollovers.
Total wheel weight (tire & rim) is part of the unsprung weight of the vehicle and will have a great effect on traction while traveling over uneven terrain as the wheel can respond quicker (lighter weight) to terrain changes. This allows the wheel to get back on the ground more quickly.

and one more link - http://www.tirerack.com/tires/tirete....jsp?techid=25

[JCL]

Originally Posted by TerminatorX5

This is from wikipedia and thus is NOT the ultimate answer - just something to take into consideration...

Pretty vague and general.

Originally Posted by TerminatorX5

Performance improvements beyond what is achieved in a Plus One sizing are minimal.

I was interested to see this line, probably because it ties in to my previously formed opinion that 18" (plus 1 from the 17" base tires) would be the sweet spot considering performance, handling, maintenance cost, and so on, without putting additional weighting on what Wikipedia euphemistically calls "culturally desirable". It also reminds us that 22" is technically a plus five sizing.

I have no idea what data someone used to come up with this line though.

[conedoctor]

Marketing has lots to do with it as well, maybe the cultural part of it, there are so many "facts" in the market right now that are totally false but if in correct uninformed info gets posted enough it becomes fact...

On that note I need to go get me a K&N air filter for better MPG and some drilled rotors with ceramic pads so I can stop faster lol

[TerminatorX5]

Originally Posted by conedoctor

stop faster lol

hmmm

is it stop faster? or stop slower??? this is a mystery!!!

[conedoctor]

Stop shorter?

[TerminatorX5]

Originally Posted by conedoctor

Stop shorter?