19" Wheels / Tyre Combo

[GarethP]

Hi folks,

I am thinking about getting a new Tyre/Wheel set for my NC but with a few goals / points to bare in mind:

1. Dont affect the gearing ratio
2. Lowest profile tyres I can get
3. Work with Mazdaspeed Springs (Lowered 90mm)
4. I am on stock 16" alloys, not the 17".
(At work at the moment so cant run out to check the tyre sizes but from websearching I think it may be 205/50/16's please correct me if wrong!)
5. I have a beginners knowledge of wheel and tyre sizes.

With this in mind I am thinking of something along the lines of:

19x8 Wheels (Such as Enkei RPF1 19x8" 48off 5/114.3)
215/30/19 Tyres (Such as Toyo PXT1-R 215/30 R 19)

Using the following (http://www.web-cars.com/cgi-bin/tirechange.pl)

The circumference of the P205/50 x 16 original tire is 75.6208 inches
The circumference of the P215/30 x 19 aftermarket tire is 75.6455 inches
Your speedometer reading is 99.9% of your true speed.
The ratio of your old vs. new tires is 0.99.

The current differential ratio is:
To retain the same overall gear ratio, you will need a differential with a 0 ratio.

Would this combination work?
Should I still aim for an offset of around 50mm?
Do I need to watch out for anything?
Is there a better way to do this?

Any input greatly appreciated.

Many thanks,

Gareth

[Brian]

You have obviously done your homework. Yes, if you gotta have 19s, then that looks like a good way to go. Just know you are doing it because you like the look of 19s, despite the fact that extra weight decreases the performance of the car and ride quality will take a major hit as compared with your 16s. My suggestion would be a compromise of 17s or 18s....but happy to get you the 19s if you want them.

[GarethP]

Hi Brian,

Thanks for the reply. You are correct, it is that tyre-on-a-diet look I so desire. The reason I picked out the RPF1's was due to the weight baring in mind all that additional metal required.

I have the 19's down as 18.7lb's how does that compare say with the stock 17's?

You mention ride quality will take a major hit? Will that just be in the bumpiness/smoothness? I dont mind a sore seat in the quest for perfection

Would there not also be slight increase in handling due to having an 8" wheel width?

Again, many thanks for the info.

Gareth

[Brian]

You are right on the money. The Enkei 19s are only a pound and a half over stock 17 inch weight. So, most of the increase in ride roughness here will be simply the reduction in sidewall cushion. And yes, since you have tried hard with this example to keep the weight down, the additional width of this setup could put you ahead in ultimate lateral grip on a smooth surface.