Tire size and MPG

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08-25-09, 10:11 AM

#16

scENFORCER

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The max tire pressure is written directly on the side of the tire (it varies depending on the tire). I usually keep it 2-3 psi below the max..

http://www.m5board.com/vbulletin/e60...5-touring.html

If the PSI is too low tires can explode due to the tire wall expanding and compressing constantly (due to uneven surfaces on the road) beyond its limits. If the PSI is too high then rough roads can cause the tire to blow also..

Last edited by scENFORCER; 08-25-09 at 10:20 AM.

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08-25-09, 12:08 PM

#17

QwkSC

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Quote:

Originally Posted by Brendon

32 psi recommended? lol i always keep my summer tires at 46 psi and my winter tires at 39 psi (5 below the maximum). What everyone says about uneven tire wear is bs. my tires are wearing pretty evenly. besides, its bragging rights to my friends to tell them my 12 year old V8 is more fuel efficient than their brand-new 4 bangers and V6s. Right now I'm averaging 25MPG with approximately 30% city, 70% highway. Not bad considering the pre-vvti SC400s were rated at 18/22 MPG by the old standards.

Yes, you can fill up the tires that high, but you are also loosing traction and compromising your handling. But hey, if you don't mind the decrease in performance and like the extra mpg then go ahead and do it.

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08-25-09, 06:04 PM

#18

Brendon

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On a stock pre-vvti SC400, its really not required. Our cars already handle like **** cornering so its not an issue, and straight line I almost never break traction. I've drag raced my friends before and even with break-torquing it to 2000 rpm, i didnt burn out. Only times I really lose traction is on dirt roads, or if the road is wet/snowed over.

Probably in the future if I do decide to supercharge my SC, then I'll drop the pressure. Since I'd be going for wider tires by that point it would make sense. On stock 225/55/16's, it really doesn't matter if you pump it up or not. I haven't noticed much difference aside from +4 MPG average.