I've had my 20"s on for about two weeks now and I love the look. They are Incubus Shylock 20 x 8.5 up front and 20 x 9.5 out back, running 255/35/20 and 275/35/20 respectively. One thing that I have noticed, though, is that my fuel mileage has decreased 5 MPG! WTF?! Is this normal for you other 20" guys/gals out there or is there something wrong with my car?

Disclaimer: I'm well aware that we don't buy Mustangs for the mpg's but come on, we're feeling it at the pumps like everyone else.[/align]

 

Yea, it will decrease. Mine went down 2 mpg when I switched to my 20" Saleen's, 275/35/20 and 295/30/20. Although I am gonna get rid of them soon. Yes, it's normal due to larger rotational mass.

 

well that sucks

 

5mpg is too much a decrease just for a wheels. Could maybe it be the new cai, tune? I noticed a slight decrease with my 20s on.

 

I don't think it's the CAI/Tune because I actually picked up 2 mpg with the combo. After the CAI/Tune and before the 20s I was up to 28 mpg on the highway, after the rims the best I've been able to get on the highway is 23 mpg. In town I averaged about 17 mpg before and now it stays around 15 mpg.

 

It depends heavily on the weight of the wheels. It's most likely from the wheels as rotational mass is always worse than static mass on mpg. Looking at the wheels I'm thinking they were built for looks and not to save weight especially on a 20 inch wheel. Plus, there is always that factor of wanting the same performance you had with your stock wheels which then creates a heavy peddle foot to compensate for the added weight and unintentionally using more gas.

 

Man, I have GOT to see a picture of those wheels called "Incubus Shylock"!!! That is one wicked name! They sound like they're more show than go.

I'm running 20' Shelby Razors at 29.5lbs ea. w/ 255/35 & 275/35's and my mpg is avg 19.4 (according to the dash computer).

 

Just checked them out. Chrome is heavy and I can't locate the weight. I'm thinking 35#+ per wheel. They look badass though.

And that name... Are you a devil worshipper or something?? j/k

 

Have you recalibrated your speedo/computer to accurately adjust for the size of the rims & tires over stock? With my 20's and 275/40 toyos, the speedo is 3mph off. That adds up over the course of 250 miles or so(avg mileage I'm getting on a tank of gas). So if your info center is telling you 19.4 avg, I'm not so sure that is 100% accurate.

 

Chrome is not heavy... That's just an old wive's tale.

As thick as the 'plating' actually is, I'd bet it's not even a fraction of what most think it is.

Any chromers out there care to share the actual facts? I know in the motorcycle world, it was also believed that chroming out your bike and rims was thought to be adding unecessary weight in lieu of "bling". And then somebody weighed all of the parts/pieces that were chromed and weighed them , and if my memory serves me right, it wasn't even a pound or two for everything. That was frame, wheels, rotors, swingarm, etc, etc, etc.