wheel alignments questions......

[cmcm]

Guys
I made an appointment for my H&R cup kit to install at one of the APR dealer next wednesday, the personel told me to drive at least 1 full week before wheel alignment.
Now, I'm still shopping my 18 or 19" wheel for my car, do I have to do 2 times on alignment or should i wait for my wheels to do it once????
I really want to do the H&R 1st to see how the stock wheels feel like.
more likely the new wheels will be on it this summer, so do I have to do the alignment once more?

[andrewt]

you need an alignment everytime you change the ride height of the car. if you just slap on new wheels and dont touch the ride height, you won't need an alignment.

[cmcm]

Thx, so if I replace the tires and wheels (18" instead of 17" stock), that minor changes the ride height, that case I need alignment, correct???

[JJ-R32]

Thx, so if I replace the tires and wheels (18" instead of 17" stock), that minor changes the ride height, that case I need alignment, correct???

When you upsize or downsize wheel sizes, you really shouldn't be changing the overall circumference of your wheels+tires. If you vary from the stock circumference you'll throw off your speedometer. So for example, when you upsize to 18" wheels, you should get tires with a sidewall height that will result in the same circumference as the stock (i.e. your new tire sidewalls will be shorter than the stock 17" tires to compensate for the larger wheels).

[cmcm]

so the 18" wheel comes with 40mm and the original 17" is 45mm, to do the calculation, there's still a minor difference:
between 18 and 17, there's a half inch drop difference (about 12.5mm, i think), but the 45mm sidewalls drop to 40, so it's a 5mm diff..or correct me if i'm wrong!!!!!

[HotLanta MKfizzle]

I think you should do allignment when increasing wheel size... Unless you are putting the new wheels on at home, they'll do at the shop as part of the work.

[Gulfer]

so the 18" wheel comes with 40mm and the original 17" is 45mm, to do the calculation, there's still a minor difference:
between 18 and 17, there's a half inch drop difference (about 12.5mm, i think), but the 45mm sidewalls drop to 40, so it's a 5mm diff..or correct me if i'm wrong!!!!!


the number 40 or 45 that you are referring to aren't in mm. They are a % of the width of the tire.

So a 225/40 tire doesn't mean 40mm in height. It means 40% of 225mm is the height.

The overall circumference will change very little, the reason most people recommend an alignment after changing wheels and tires is that if you are changing the set usually ure old tires were worn and its been a long time since youve gotten an alignment and hence your setup is probably off from use over time. You wont need a second alignment if you are changing ure wheels/tires only a few months after u get the original alignment.

[cmcm]

thx gulfer

[GTI2007]

I used the tire size calculator on http://www.1010tires.com/TireSizeCalculator.asp and made a screenshot from it to show you how small the difference is between the 17, 18 and 19" wheels for the GTI

[Gulfer]

Just as a FYI, we also have a similar wheels and tire calculator here, just click the red box on the top of the page in this wheels/tires section and an easy to use box should appear, hope it helps in the future.

[cmcm]

thanks guys, I gain lots of knowledge after I joined this forum, especially the wheels and suspension concept which usually confused me.