***245/40/18*** With 18 X 7.5

[AleroBloke]

pros and cons please,,pictures would help pleas..asap

[AlbinoMonkeyRat]

245/40 is too big for 18's (for the speedometer thing), 245/35 is perfect on 18's though. But if you know a place that will recalibrate your speedometer, 245/40 will fill out the wheel well a lot better.

[tnalero99]

I have 235/40 18s and they fill the wheel well fine without rubbing with eibach springs on my car. I don't know the wheel offset because I bought them used.

[bigd6983]

245 is wheel width, i dont think that has anything to do with throwing the speedo off, the series of the tire will whether its 35 or 40..........i just dont see what the width has to do with the diameter of the wheel

[gre0481]

say a 245 40 18 is your tire

245 is your width, 40 is the girsth of the tire, like measuring from the bead or rim to the read

18 is the opening for your rim.

Having your speedo a little slower wouldn't be too bad. actaully might help youavoid a few tickets :P

245 might be pushing it, I'm not saying it's too wide.

Wait and see if anyone else has 245's. I think I saw somewhere someone had 255's. But then again, they had air, so they could just bump it up a bit when they drove

good luck

[Oldsman]

actually a 245/35 would be just a little wider than a 245/40

either one will fit fine. the 245/35 r18 would keep your speedo close to accurate. with a 245/40 you will be off by approx 3 mph.

i have 255/40 r18 on 18x7.5 with 42mm offset and they fit fine. but that is max width and diameter right there. oh not running air.

[RoninKouga]

Originally posted by Oldsman@Jul 23 2005, 10:49 AM
actually a 245/35 would be just a little wider than a 245/40

either one will fit fine. the 245/35 r18 would keep your speedo close to accurate. with a 245/40 you will be off by approx 3 mph.

i have 255/40 r18 on 18x7.5 with 42mm offset and they fit fine. but that is max width and diameter right there. oh not running air.
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we have strict official rules here about tire sizes .. too bad

considering that the original measurements for the alero are:

215&60, 6x15@ 42mm offset

oldsmans wheel circumference is plus 3,47 percent, so the speed change is.
in wideness the tires are coming out of the wheel holes +1,91 centimeters with 42mm offset. it wouldnt be allowed in germany coz we have a 2 percent limit.

245/35 would be minus 1,46 percent, its / like oldsman said the close to stock.

my opitimum size for the ho is following

225/40 theire not too expensive
8x18 rim, (as wider the rim is as wider appears the tire to be)
Offset 40 mm

with this measurements the changes will be the following

- tire gummi size over the rim will decrease from 12,9cm to 9,0cm
- tire circumference / speedo change -0.28 percent
- the tire will be coming out of the hole +2.74 cm in wideness (2.54cm w/ offset 42)

think id look best :biggrin:

hey oldsman do you think there will be enough space for another 1 cm tire wideness in the fender?

[RoninKouga]

ok 225/35 8x19'' ET42

is even better for alero, if you dont want tires that look like a baloon hehehe

its +0.17percent in circumference
and the tire height over the rim is increased by 5.03cm to be 7.88cm now.

AS FOR THE TOPIC .... XD

245/40 w/ 7.5 *18 OFFS 45

i wouldnt take this tires coz of the higher offset the track widht will be reduced for half a centimeter then stock. not too good for driving fast curves hehehe

the speedo change with tis configuration will be 2.something percent

edit: note that not only the speedo changes in the mentioned percentages, ur all over transaxle and so the performance does. increasing tire height: slover acclerating, higher top speed. fewer height: more accleration power, less top speed.

your estimated shifting points will lower or rise with it too

[Redog]

45 is the wrong offset, they won't work.

I had a set of 17's with a 45 offset that I had from my Cavalier and when I put them on my Alero they would rub the rotors and wobble like crazy. I bought spacers to fix the problem, only to have to buy longer wheel studs from GM racing, that wouldn't fit.

Offset must be between +38 to +42. the 16" stock wheels are a +40 offset

18 x 7.5 will fit as long as you put a 235 / 40 / 18 tires on them, but it's gives you one hell of a narrow sidewall. Watch your bumps and potholes

[Oldsman]

Originally posted by RoninKouga@Jul 23 2005, 06:45 AM
hey oldsman do you think there will be enough space for another 1 cm tire wideness in the fender?
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oh there is enough room.

actually my 18's don't come out pass the fender. they are almost even.

[AleroBloke]

Thanks guys. I bought them yesterday, cuz the car it was on the engine siezed up. so the guy sold them to me for 100 bucks..pretty good deal i thought for only having them on his car for 3 days. so we will see today.

[RoninKouga]

Originally posted by Oldsman@Jul 23 2005, 05:07 PM

oh there is enough room.

actually my 18's don't come out pass the fender. they are almost even.
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would you make a pic for me where i can see it? coz if it comes out with this 1 cm more i am not allowed to install. ;)

thanx

[Oldsman]

here is the 18's on the front of my car. they are spaced out .125 for extra clearance for the coilovers.

[RoninKouga]

wow thank you, oldsman

ITS GORGEOUS!

[RoninKouga]

they are spaced out .125 for extra clearance for the coilovers.


gotta admit i dont quite get that.. u got your fenders wider? both, front and rear?

[AlbinoMonkeyRat]

no...lol...he's got .125" spacers on the front wheels so they don't rub the coilovers. Probably didn't touch before, but came close...so with the spacers, there's no doubt that they won't touch. ;)

[Oldsman]

Originally posted by AlbinoMonkeyRat@Jul 24 2005, 12:54 PM
no...lol...he's got .125" spacers on the front wheels so they don't rub the coilovers. Probably didn't touch before, but came close...so with the spacers, there's no doubt that they won't touch. ;)
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yep

[FormulaNERD]

Originally posted by bigd6983@Jul 22 2005, 10:49 PM
245 is wheel width, i dont think that has anything to do with throwing the speedo off, the series of the tire will whether its 35 or 40..........i just dont see what the width has to do with the diameter of the wheel
Quoted post



the wheel width has EVERYTHING to do with throwing of your speedo. because the "series of the tire" i.e. 30, 35, 40, is the PERCENTAGE of the sidewall (245)

to keep your speedo accurate, you want your OVERALL Diameter to be the same.

use the miata tire calc.

[AleroBloke]

Let me ad this. I bought some sprint springs aswell....would that effect.. I am posotive that my offset is +45 i am looking at the box my rims came in right now. I am hearing alot of peeps that say it will fit. I don't have any spacers on my car. I know that from reading, oldsman does. but I guess i just have to fiddle around and see if it fits....say if it doesn't where can i get spacers? and how big should i get them?

[Oldsman]

far spacers...........well if you have to space then the only way to know for sure the thickness is by mounting the rims and tires and measuring to find out for sure your right thickness