Tire Help

I know this has been discussed a million times but I did a search here and read and read and read. And, as usual, the more info I absorb the more confused I get.
So here I am - I'll be putting new tires on in the next week or so. I'd planned on the Yoki's below, but now I'm concerned about the diameter issue. I currently run 165's and they are somewhere in the 25" dia range. How much of a difference will the smaller diameter make?
With the new engine the 165's let go with the flick of my foot so definitely need more rubber. I have 4.5" wheels that I plan to keep. Especially now that the 5.5"s are getting harder and harder to find. Plus I'm still pretty pinched with space, although it's to the inside now.
Please give it to me straight. What do I need to concern myself with? Thanks, Mickey


http://www.tirerack.com/tires/tires.jsp?tireMake=Yokohama&tireModel=ADVAN+A043&vehicleSearch=false&partnum=855VR5043&fromCompare1=yes&place=2ow.

185 x 65 15's no issue at all.

It's going to be awful dang funny to see GOOD~YEAR spray-painted over Yokohama.

before you pick that particular tire - check out the survey results:

http://www.tirerack.com/tires/surveyresults/surveydisplay.jsp?type=ST

http://www.tirerack.com/tires/surveyresults/index.jsp


also - check this out for tire size:
http://www.miata.net/garage/tirecalc.html

I'm running 185-60-15 it's a squeeze front and rear. as you know - i narrowed the rear quite a bit, and this winter i'm going to narrow the front 2-3"

Thanks Paul.
There are only two tires available in 185/55-15 Ultra High Performance Summer and the Yokohama is rated the highest. Excellent in cornering, steering response, and dry handling. And only OK in wet, hydrolaning and treadwear. The difference between my current size and they ones I'm looking at is 794 revolutions per mile versus 876 per mile. That's a difference of 82 more revolutions per mile with the Yokohamas.

I just talked to Cory. He was esplanen to me that it's not so bad to have a smaller tire with a thinner side wall as it will translate power better and therefore NOT put undo stress on the engine. I know that makes sense in "everyday, normal" cars, but does the same principal apply to our cars, being that they have somewhat antiquated suspension systems and are so light up front.

My wants, needs, concerns, ect... in a tire are as follows - I'm looking for performance first and foremost. I want sticky! I know the tendency for our cars is to push in hard cornering because of the light front end so the more grip up there the better. My concerns are space and putting too small a tire (diameter wise) on and therefore making the engine work harder to turn the wheels faster, if that makes sense. I rarely drive my car in the rain and NEVER in the snow. It goes into storage pretty much from mid November to early March.
I'm not much of a physics guy, it makes my brain hurt. So any input on this stuff is appreciated. I'm gonna call Cory's dad this week because he's one of them smart fellas that works for Michelin. But I think I'm a little limited when it comes to sizing with having 4.5 x 15 wheels. I want to know what other guys with the same size wheel are running and what their experience is with what they have.

Mickey, I just sent that to him. The other stuff he said he'd need is in your e-mail.

The charts I have seen recommend a minimum of 5" wheel width for 185-65-15.

185-65-15 works just fine on a 4.5" rim. Vintage Spyders has been doing it that way for years. Early 911 owners use 195/65 15, as that is closer to the OE diameter, but won't fit a 4.5" rim. I would recommend 185-65-15 for the front, and if you have 5.5" in the rear, either 195 or 205/60-15 in the back(I run 195). The Spyder guys all highly recommend the Bridgestone RE960 Pole Positions, I will be buying them when I replace my current tires. Good luck.

Mickey,
Go with Yokohoma Avid H4s. Offered in a 185/65/15.
It's not Ultra high performance but it is all-season high performance.
I've used them for years and am very happy with the handling. The sidewall height is relatively close to the stock tires and the ride is more comfortable than a 60 tire.
Although you can mount them on a 4.5 wheel, the performance isn't as good as on a 5.5.
http://www.tirerack.com/tires/tires.jsp?tireMake=Yokohama&tireModel=AVID+H4S

i'm also running the Yoko's Terry is, but in a slightly lower profile. (60)

the overall diameter of the tire is what effects acceleration. It doesn't put more "load" on the engine. It changes the speed / RPM relationship as well as how fast you accelerate. tiny tires (like 35 series would make you accelerate crazy fast, while putting big off-road tires on would slow down your acceleration, but increase your top speed. if we are talking about 5-10 aspect ratio points in the sidewall (55-65), then you would not notice it a lot - although you would notice it. The biggest factor of change would be ride quality and looks. larger side wall - more comfortable ride.