SO2 poles

I put So2 poles on my 88 Carrera about 1000 mi's ago.THEY ARE 245X45X16 AND 225X55X16 mounted on 7 and 8 Fuchs.This coupe is new to me and so I don't have a relative comparison but they were highly recommended by several people and are very adherent. I'm absolutely sure I haven't come close to thier limit but have managed to challenge myself a few times and that haven't even squeeled.
HOWEVER on the Fwy when the cars around me seem to be doing speed limit (65 +or-)my speedo is reading 80mph. Is the tire difference so great in terms of recommended size that it would make a 10+ mph difference at 65 mph? If in fact that is the case then the odometer reading is going to be off as well by 12+%.An actual 88mi would read 100 on the odometer? Not good for resale value or adequate service info.Are 245's actually too wide for this wheel (8x16)on the street and what would the correct height and width be for accurate speedo and odo readings? By the way the so2 poles don't come in 245x 50 or 55 just the 245x45 configuration.
Thanks for responding to such a elemetary inquiry.
Michael

I don't know about where you live, but here in Atlanta, the people on the freeway seem to be going about 75 mph when the speed limit is 60 or 65...so you can't guage speed by others. The best way to find out would be to get a friend who has a fairly new car...or a car that has relatively stock tires and go a certain speed. Another thing to do is figure out what the rolling diameter of the stock tire would be for your year and compare it to that of the tire you have.

Hope this helps,
Paul

The stock tire size is 205/55 16 in the front, and 225/50 16 in the rear.

Your rear 245/45 16s are close to the stock height/diameter, but actually are little shorter than the stock tires (at least by my calculation), which will make the speedo read a little high. But, the overall diameter is close enough to stock to not make a significant difference.

Did you specifically request those non-stock sizes, or did the tire store just put those on?!? Do you get any rubbing in the front?

Brian

[This message has been edited by Brian Kumamoto (edited 02-24-2000).]

Are those the recommended sizes? On my original fuch's, the sizes are 205 55 16 and 225 50 16. When I changed to 17" 8" and 9", those dimensions changed to 225 45 17 and 255 40 17, keeping the same aspect ratio front and back. I must of checked a dozen times with people from Fikse, the TireRack, and Wheelenhancement before I ordered. I have a volvo S80 that I was thinking of putting beefier tires on and might have to go up from 50 series to 55. I think the margin of error the man from the Tirerack said was something less then 3%.
Mike 89 3.2 911 Coupe

According to the Bridgestone site the 245's are 24.6" with an rpm (rev per mile) of 847 -- the 225's that were stock are 24.9" with an rpm of 837 or about a 1.2% difference

Use this site to calculate difference in tire sizes. http://www.powerdog.com/tiresize.cgi
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Diameter
225/50/16 = 24.9
245/45/16 = 24.7
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Circumference
225s = 78.1
245s = 77.5
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Revolutions
225s = 811/mi
245s = 817/mi
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Difference
225s = 0%
245s = -0.7%
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This is such a minor difference you should not notice any difference in speedo readouts. I recently changed Fuchs 7 inch /225 to Fuchs 8 inch /245 in the rear on my 83SC - I noticed absolutely no difference in rpm to speedo reading betweem the two. Relative speeds to other traffic remained the same.
I wouldn't worry - you have a very nice set up! Stick with it and enjoy!

Thank you gentlemen,
for all the elaborative information.The size choice was based on what was mounted when I purchased the coupe. The tire was chosen the way the posts on this board suggest.I then had them shipped from Tire Rack and dropped at a local installer . Mounting ,balancing and front end allign. $110. I wish now I'd had the four wheels alligned and balanced at each corner., next time.
By the way anyone have experience in relation to the best tire pressure to run in these for street use ? 245x45x16 and 225x55x16 mounted on 7&8 Fuchs.
This board is the best.
Thanks,
Michael

I think I'd probably just run the stock tire pressures.

Brian

hey "89911"

i have a question regarding the tire sizes the fikse web site recommends for running 17" 8's & 9's after you stated you checked with them. their web site suggest that for these specific wheel sizes, use 225/40-17's for the front & 245/40-17's in the rear. http://www.fikse.com/fitments.html#oo. i have not been able to even find a tire that is size of 225/40-17, so that info on the fikse site has to be a typo, right? my question is this, if you are running 255/40-17's in the rear, do they rub at all? second, have you lowered your car, or is it at standard u.s. bumper law heights? thanks man!


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'84 911 carrera cab.




[This message has been edited by jeff bryant (edited 03-01-2000).]

I installed a set of aftermarket 17' C2 Carrera cup wheels along with four Bridgestone RE71 205-50-17s and 255-40-17s on my 79 SC. I have lowered the car slightly in the front. . .just enough to look correct, and left the rear alone as it didn't look too high. The car looks great and there is no rubbing (even though when I pulled them out of the box I said to myself. . ."theres no way these will fit").

My only question from the posts above is... Can anything wider than a 205-50-17s be put on the front of my SC? It seems that some people say it can be done, but the gentleman at WheelEnhancement said it wouldn't work. The only reason I am curious is because the 205s have a different look to their profile from the side and it dosen't seem to look quite right on the car. I figure that a slightly wider tire (225) would look better.
Any thoughts?
Leland