Where to start?

[Laxpunk2006]

I'd looking at upgrading to some nice 18 inch wheels but I've realized if I do that my car might sit a little high. So I was wondering where to start on my suspension to maybe lower it about an inch or two and help with handling soon. I'm not looking to spend a ton of money because I still have to buy the wheels/tires and I'm saving to buy an m3 next summer so there's no point in dumping aton of money into this car if I'll be replacing it in about a year.

[TiredTi]

Where to start, you ask?

First, you need to decide if bigger wheels is the right first step. Bigger wheels look cool, and they have more room for a big brake kit, but otherwise, they are a bad idea.

Reasons why you DON’T want bigger wheels:
- bigger wheels are more prone to on-road damage from pot-holes etc.
- bigger wheels make your car slower (more rotating inertia)
- bigger wheels are more expensive, and tires for bigger wheels are MUCH more expensive
- bigger wheels make your car slower
- bigger wheels (well, wider ones) will make your car tramline worse
- bigger wheels may not fit in your wheel wells (must be very careful with tires, offset, etc.)
- bigger wheels make your car slower (did I mention that already?)
- bigger wheels ride more harshly
- bigger wheels (wider ones anyway) will increase your fuel consumption

If you put on bigger wheels and tires that give you a larger outside diameter of the tire, then you are effectively raising the gearing on the car, and your speedometer will be off, and you will make the car slower.

So, once you’ve decided whether or not to spend for the big wheels… then think about suspension.

When you consider lowering, first decide why, and how much. If your car is a ‘sport’ model, it is already lower than stock. (Sport springs are shorter than stock springs.) If your car is not a sport model, then you may wish to buy BMW Sport springs, or others.

Now, lowering can make your car look really cool, and it can make it handle turns better (lower centre of gravity) but it will ride harder. I have a sport, and I think it is low enough for good handling, with reasonable ride quality. For the track, lower yet would be better.

If you are considering springs, you should consider shocks. Read the archives here for lots of info on Koni or Bilstein. Coil-overs by Ground Control are even better.

And why not think about larger anti-sway bars. These might actually be the best handling improvement you could consider on our little cars, at a reasonable cost.

I could go on, but I think I will wait for your response, and the input of others, before I do.

Looking forward to your reply,

Steven Park
Burlington CANADA

[moku]

Comments on TiredTi's statements:

"bigger wheels are more prone to on-road damage from pot-holes etc."
True, but it depends on the profile of your tire. 17s with 45 series tires are less prone than 19s with 35 series tires. Plus, it will also depend on how rough you drive, the kinds of roads you drive on, and the kind of wheels you have. Forged wheels are very strong. So, there is some middle-ground.

"bigger wheels make your car slower (more rotating inertia)"
If you plus-size your new sets of wheels and tires correctly, the overall diameter and circumference should be about the same as your stock wheels, making this less of an issue.

"bigger wheels are more expensive, and tires for bigger wheels are MUCH more expensive"
True, but you also get more tire and generally better performance for the extra money. A wider tire will also give you a bigger contact patch, which will make for better traction.

"bigger wheels make your car slower"
Depends on if you plus-sized correctly and the weight of your new wheels. For example, my 17" BBS RKs are only 17 lbs each and I've plus-sized them so that they're almost the same size as my stock 5-spoke wheels. And I didn't find my car to be any slower (and that was before the supercharger).

"bigger wheels (well, wider ones) will make your car tramline worse"
This is true, but it's not that terrible that you lose complete control of your car. All widths of tires experience tramline, just varying degrees.

"bigger wheels may not fit in your wheel wells (must be very careful with tires, offset, etc.)"
If you plus-size correctly, this isn't an issue.

"bigger wheels make your car slower (did I mention that already?)"
Again, depends on if you plus-sized correctly and the weight of the new wheels and tires.

"bigger wheels ride more harshly"
This is subjective and will depend on your definition of "harsh". Some people like to feel the road, while other want a more cushioned ride. Just depends on your personal preference. Your shocks and springs will also be a factor here.

"bigger wheels (wider ones anyway) will increase your fuel consumption"
I think your driving patterns have more affect on your fuel consumption than your tires. Plus-sizing, again, is the key.

People's cars and modifications are a personal thing and everyone does what they feel works for them. TiredTi may not like large wheels and tires, but that doesn't necessarily mean you shouldn't. Conversely, I like large wheels and tires but that doesn't necessarily mean you should.

In the end, if you want to get bigger wheels and tires, go for it. Get informed (which is the beauty of these kinds of forums) and then make an educated decision.

Good luck with whatever you decide.

[Laxpunk2006]

Besides obviously for looks, I wanted the bigger wheels so I can have a little bit wider tires for some more grip. Mainly what I'm looking for here is what am I going to need to make my car sit nicely on a set of 17's or 18's. Will just springs do and if so do you have any specific suggestions?

[moku]

Originally Posted by Laxpunk2006

Besides obviously for looks, I wanted the bigger wheels so I can have a little bit wider tires for some more grip. Mainly what I'm looking for here is what am I going to need to make my car sit nicely on a set of 17's or 18's. Will just springs do and if so do you have any specific suggestions?

If you're going to upgrade your suspension, get both springs and shocks. Your stock shocks won't last long with the shorter springs.

Here are some common springs & shocks:

Springs
- Eibach Pro-Kit (about a 1.25" drop): hard to come by because they've been discontinued for our cars but good springs.
- BavAuto Sport Springs (about 1.5" drop): affordable and made by the same company that makes the BMW OEM springs.
- H&R Sports (about 1.5"-1.75" drop): Quality springs that are fairly popular for our cars.
- Vogtland Sports (about 1.5"-1.75" drop): these are German-made aftermarket springs that I've heard are pretty good.

Shocks
- Bilstein Sports: made specifically for shorter springs and have a limited lifetime warranty. Not adjustable.
- Koni Sport: quality shocks that are externally adjustable.

There are some coilover systems from Bilstein, Koni and H&R, if you want to get a fully adjustable system. Just make sure you'll have enough room to fit your wheels, because I know that you have to run spacers with certain setups.

Overall, H&R/Bilstien or H&R/Koni are popular setups. I opted to go with BavAuto springs and Bilstein Sport shocks, and I like both the look and feel.