Hyperlite

The car is in the shop getting lowered right now and I'm concerned about rubbing the front fenders and when went back and looked at my tire size I was a bit confused. So if someone less tire-impaired than I could clear it up for me I would appreciate it...

I've got Continental Extreme Contact DW's

On the front - 245/40ZR18

On the rear - 275/35ZR18


Now what confused me is, from what i understand when looking at this.

It seems like my front tires are taller than my rears, the only other thing I could come up with is the tire height number correlates with the width so /40, would not be the same height for all widths...


Can someone help me out...

HeissRod

Front - 25.7" diameter
Rear - 25.6" diameter

The difference is 3.5mm. It's all in your head.

http://www.miata.net/garage/tirecalc.html

Hellzno

the front fenders on the e55 will not rub. they are physically cut higher than the rear. The rear will rub before the fronts but you should be fine with 18's. Are you getting star lowered.....star lowered will not go low enough for you too rub. Maybe if you add like 6 washers plus star.

tire width/tire profile (this number is percentage of width)/ rim diameter

above explains the tire sizing numbers.

Hyperlite

This is why I love you guys.

@Hellzno

StarLowered



Thanks

wsybert

The middle number is the aspect ratio or percentage of height to width. So take 40% of 245 for the front, and 35% of 275 for the rear. That will be your sidewall height in millimeters.
To get overall diameter, convert the mm to inches, multiply by 2 and add the rim diameter (18).

HeissRod

If you're trying to understand tire dimensions, then it breaks down like so. I'll use your 245/40_18 for the math.

245 = tire width measured in mm
40 = aspect ratio or sidewall size
18 = rim size measured in inches

To find the diameter of the tire, you take the aspect ratio as a percentage of the tire width. In this case, the aspect ratio would be 98mm (245 x .4). If we add it all together, we get the overall diameter of the tire.

Wheel size = 18" or 457.2mm
Aspect ratio = 98mm (x2 since there is a sidewall above and below the rim)
Overall diameter = 653.2mm or 25.7"
(1" = 25.4mm)

Your rear tire would be....
Wheel size = 18" or 457.2mm
Aspect ratio = 96.25mm (x2 since there is a sidewall above and below the rim)
Overall diameter = 649.7mm or 25.6"

Hyperlite

I know Hellzno already said I wouldn't get any rubbing.

But

Is anyone else positive that I won't get rubbing with these tire sizes if I am only lowering with through star??

HeissRod

Based on tire dimensions alone? No. Your rear tire is 1mm smaller in diameter than mine and I don't rub under Star lowering.

I can't speak for your wheel offsets and widths, though.