MX-3.com

So recently several people have told me the RS and GS used the same tire sizes, and this may be known to most but thought since I have heard it from a few I would put out the info just so we have it. Having both an RS and GS I have checked this and they are in fact different.

All factory GS models came with 15" wheels and the RS came with 14" so the tire sizes are as indicated below.

GS Wheel
Wheel size - 15"
Tire size - 205/55-15
width - 205 mm (8.1'')
Sidewall - 113 mm (4.4'')
diameter - 607 mm (23.9'')
Circumference - 1906 mm (75'')

RS Wheel
Wheel size - 14"
Tire size - 185/65-14
width - 185 mm (7.3'')
Sidewall - 120 mm (4.7'')
diameter - 596 mm (23.5'')
Circumference - 1871 mm (73.7'')


So as you can see they are different, not by much but they are. So when sizing up you should check the appropriate tire sizes.
Here is a good calculator I found for comparing. http://www.rimsntires.com/specs.jsp

This is enough different that when sizing up and getting new wheels say to 17" the proper size for a GS would be 215/40/17 and would put the tire Diameter at 23.8" only .1" different. If you were to size the RS up to 17" wheels the proper size would be a 205/40/17 and would put the diameter at the same 23.5". I know we are only talking a few mm's here but that is the difference of potentially getting a ticket in a school zone and not.

IDK, check out the calculator and play with the offsets too. It is kind of fun, it does all the calculations for you.

FAQ!!

kulluminati777 wrote:FAQ!!

AGREED!

+1

Isn't this already in the FAQ? It's on the main page.

Looks like there is http://mx-3.com/phpBB3/viewtopic.php?f=36&t=36492 but it is kind of laid out funny and harder to read. IDK I just thought since recently it has come up in conversation with a few people that it would be good to put the info out there. Perhaps someone could just add my comment to the bottom of that thread.

Josh wrote:I know we are only talking a few mm's here but that is the difference of potentially getting a ticket in a school zone and not.

Lol, really? Don't scare people here. Remember too that it's a ratio, so the faster you go, the more the speedometer will be off, so in a school zone, your registered speed would be even more negligible than tire wear....

I ran 205/40/17 on the Mx-3. I GPS confirmed my cluster to be exact with my Speedhut overlay.

On my truck, the original tire size is 265/65/17 and I'm currently running a 32x10.5r15. The difference in diameter is about a full 2" (I measured the tire and it was 32.5" new because of the narrower rim). Mind you the tires are a few years old now, but a few weeks ago and I was driving back from Qc with my parents following me in their Civic ('09 with the digital speedo) and if I'm doing 100km/h on my speedo, I'm actually doing 110km/h.

lol that is why I said "potentially"

But yeah, the slower you go the closer it will be. But this also effects your fuel mileage as well. If you are like me and keep track of your mileage every time you fill up it makes a huge dent. Currently I am running 205/40/17and I have already noticed a difference in my MPG's.

How much have you seen? I'm gonna be running a 205/45/16 or something close and was wondering.

If you see a difference in mileage and have a similar circumference, the cause is unsprung weight and overcoming rotational inertia which will also make your brakes work harder to stop at the same distance as a stock wheel/tire combo. That is where you want to get as close to the stock wheel/tire weight to gain optimum performance but also assuring you have adequate grip to put down the power as well, so it'll always be somewhat of a compromise.

I just went from 225/50/15's to 205/40/17's and I have seen a reduction in mileage so far, but I have only gone through one tank and i bought it from a location I normally do not go, and the tire diameter is only less by .3" or 11mm not a lot. The biggest difference is going from the 11lb wheels I had to the 22lb monsters I have on it now. After this tank of fuel I will have a lot better idea. So far I am at 200 miles and have 1/4 tank left. Usually I will get about 220-240 when the light comes on and that is almost exactly 10 gallons when I fill up.

My new 16" wheels should be coming soon, they will be lighter

Nice info redline. Thanks.

Nice josh, I just got 01 miata 5 spokes.

Nice choice, I was going to get a set of those but decided on a set of Miata SE wheels instead.

Nice. I'm hopefully painting them soon, Looking at a orange not sure, on shade or anything yet, my GF's choice, and I thought it would go with the metallic raspberry, nicely.

When I moved from the stockers, that`s all I ran was 205/40 on my Konig 17's and never had issues with mileage where it was always superb

Nd4SpdSe wrote:When I moved from the stockers, that`s all I ran was 205/40 on my Konig 17's and never had issues with mileage where it was always superb

Well I ran these same wheels on my RS and when it was N/A and an ATX these wheels made it pretty gutless and reduced my mileage from 34mpg to about 31mpg. But with boost and over 230 WHP I never cared, that is why I bought them. I even ran oversized tires most of the time with 215's as to limit my wheel slippage. I got a killer deal from a buddy on the 205 AVS ES100's I am running so I couldn't pass it up at the time. But after going through a couple of tanks in the GS I am down just a little over 1mpg. When I go to the 16's with the 205/45's it should go back up. I am averaging about 26.5MPG right now and I was in the higher 27's.