Do you need to realign the car if you buy bigger wheels?

[2000GTS]

I am thinking about going to 19's or 20's. Will I need to realign the car?

Bill

 

[Janni]

If your rolling diameter changes and your ride height changes, then, yes - you will slightly change the alignment.

 

[Purdue_Boiler_Viper]

OK, I'll bite. Educate me, please. Why does rolling diameter and ride height mean an alignment change?

Thanks,
Pat

 

[George Farris]

Go Irish!!!

 

[Anaconda]

You know, it is a good idea to get the car aligned periodically regardless...and it's not expensive. If you are swapping wheels, why would you NOT get an alignment??

 

[Janni]

When you raise the ride height I believe it effectively lessens your negative camber. Lowering it will increase negative camber. You can see it in an exaggerated form with the "slammed" cars - when they are WAY down, it looks like the wheels are seriously splayed out. It;s possible that the wheel change will do it to a lesser extent than adjustable shocks, I'll ask the technical advisor to be sure.....


We see these effects when we play around with ride height on the race cars doing alignments on the scales at home.

 

[Steamroller]

Janni... I do not see how changing the ride height by only changing the rolling diameter would change the resting suspension geometry. Yes, the ride height changes, but the suspension still physically rests in the same location relative to the car. Using a different rolling diameter simply changes the distance from the centerline of the wheel to the ground. If the rolling diameter increases by two inches, then the wheel's centerline will be one inch higher off of the ground... so would the entire car. Thus, the suspension's resting position relative to the car would remain the same. This analogy can be demonstrated by simply driving a car onto a set of one-inch thick blocks. Yes, the car is higher off the ground, but the suspension's resting geometry does not change since the suspension did not move relative to the car.