I have a bunch of questions about this stuff. Hopefully someone can point me in the right direction about some of this stuff.

I'm getting some idea of what offset is, but I'm still not !00% sure what units the offset is in, and how it relates to the tire size - if at all. I also don't know what the different numbers in the tire spec mean, and how they relate to the rim size.

In my TL manual, it says you shouldn't use different spec'ed rims or tires than the stock ones, yet everyone here seems to be breaking that rule. Acura claims it will mess up the traction control system etc. Is this true?

How can I figure out what sizes of rims, offset, tires etc. I can safely use? Is it just a matter of reading here and seeing what everyone else is getting away with?

What is the difference between coilovers and shocks and springs? From the pics, a coilover just looks like a package of shocks and springs together. Is this all they are?

Is there any product (but not hydraulics) that will allow me to easily raise my car for the winter but drop it in the summer, without having to replace springs etc. each time?

...you can probably see now why I chose 'CarDumb' as my alias.

 

Offset has to do with tire width as I understand. If you go for example with 18x8 or 19x8 your offset should be 50+ or more. If you are buying a package, then you tell them what you want and you will get it. Offset does not relate to tire size. It is how far does the rim stick out of the wheel well. The more it sticks out the more chace the tires will rub.

A Coilover is a package of shocks and springs. What you can try to find is a system where the shocks will allow you to raise and lower the car which would be better for you.
In my setup I'm running H&R Sports, when my stock shocks go out I will go with Koni Yellows shocks which will allow me to raise and lower my car.

Also take into consideration that whenever you drop your car (mostly rear) about 1.75 inch or more you are likely to screw up your camber and will have to spend money on a camber kit to make your tires look straight like so || (with a camber they might look like: / (car here) \ ) Camber varies from car to car, with my drop after the alignment my camber was fine, another person with the same setup as me might have a bad camber.

 

A good place to start would be here. Members have posted their wheel and tire specs and also indicated if they encountered any problems with a specific combination.
Click here for a explanation on wheel offset.
Happy reading..

 

I have been reading here, and have actually already read that FAQ (forgot about the mm as the units for offset though). What I still don't get is whether +'ve offset means the wheel is closer to the centre of the car or further out towards the outside of the car. The FAQ talks about 'left' and 'right' but that's a matter of perspective, so I'm still not sure what offset I need.

Also a number of articles here talk about rolling the fenders. Does that mean bending the fenders to create a larger circumference hole in the car's body? (This is definitely something I won't want to do on a leased car).

The FAQ talks about 3 piece wheels too - what are they, and why do they help the situation?

 

then think of it was inner and outer...inner rim half being towards the car's centerline while the outer rim half being towards the perimeter of the car. postive offset indicates the location of the hub mounting surface being towards the OUTER rim half. conversely, negative offset indicates the location of the hub mounting surface being towards the INNER rim half. and of course, there is zero offset where the hub mounting surface is in the plane of the wheel's centerline. the higher the number, the farther the hub mounting surface is from the wheel's centerline. a wheel with a zero offset means that half of the rim is in front of the rotor and the other half is behind. a positive offset means that more of the rim width is behind the rotor than in front...ie, less chances of rubbing the fender. a negative offset means more of the rim width in front of the rotor...ie, more chances of rubbing the fender. however, this is where rim (and tire) width play a part in rubbing. if you get too wide of a rim, you have less room to play with so you need an exact offset. if you get a fairly narrow width, you have more room so a number of offsets will work. also there is a fine line where you can get too over cautious and have rubbing occur along the inside, but more likely than not, this won't happen because a lot of wheel makers do not offer super high offsets!

 

if you examine the fender area, especially the rear, you will see a flat wide lip following the arch of the wheel wells. this is the lip that protrudes into the wheel well and can cause rubbing against the tire if your setup is not mounted deep enough (due to not having a higher eoungh positive offset on our cars). you can't leave this alone because the lip can cut the tire. so if you are rubbing, you will need to roll it (ie, bend) upwards to get it out of the way...or, just cut it off as much as you need.

 

the number of pieces basically tells us how the wheels are contructed but in true life terms, it tells us how expensive the wheels are!!! 1 piece means it's made from a mold where metal is melted and poured in...or the metal is slightly melted to a glob and then forced into a mold (this is called forging)..or it can be a solid block of billet aluminum and you carve out a wheel. 2 piece wheels is composed of the rim cylinder and wheel face. the rim cylinder will most likely be spun from aluminum while the wheel face can be made from a variety of processes. a 3 piece wheel basically breaks down the rim cylinder into two pieces plus the wheel face. since a wheel is composed of separate