275/40/18

BrettT 93|03

93 & 03 Cobra Venom
Established Member
Joined
Jun 15, 2004
Messages
428
Location
Maryland
Anybody running 275/40/(18's) on the front??? Any pictures??

Lowered the cobra with h&r race. Not happy with the front drop. Was thinking of going with the oem tire spec but in a (18") size wheel. I think the taller side wall will help with the look without having to take the ISO's out of the front.


I have 275/35/18 on it now
Thanks
 
Last edited:

tt335ci03cobra

Well-Known Member
Established Member
Joined
Feb 15, 2008
Messages
6,958
Location
USA
The 40 vs the 35 would only be a slight difference, for comparison the 2000 cobra r came factory with 265/40/18. that equates to 26.42" tall so you can look online and see if you like how those sit ( they were low ride height wise factory, pretty much as low as you can get that car.) 275/40/18's would be only slightly taller at 26.74" tall so its literally only a 1/2" difference over a cobra r setup. hope that helps for a reference .

the conversion formula is as follows: tread-width multiplied by sidewall as a percentage out of 100 (ie a 40 side wall would be 40% of the tread-width, a 70 would be 70% of the tread-width.). with that resulting number, divide it by 25.2 ( the number of millimeters in an inch). then multiply that number by 2 (top and bottom sections of the sidewall with the rim in between those areas of course) then add to that number the rim diameter in inches. so example:

275/40/17: 275*40%= 110. 110/25.2=4.37. (4.37*2)+17=25.74" or roughly 25 and 3/4" tall.

reference heights

-factory 03 cobra @ 275/40/17 = 25.74" ( 25 & 3/4")
-factory 00 cobra r @ 265/40/18 = 26.42" (26 & 1/2")
-your thoughts of a 275/40/18 = 26.74" (26 & 3/4") (roughly 1/2" taller sidewall above and below the rim. 1" taller altogether over your current setup)

all of these fit a mustang fine. do it, it'd look sick if you ask me. I am going to do a similar setup with ~26" (f) and ~27" (r)
(285/35/18) (25.92") (f) nt05s/nto1 nittos
(325/35/18) (27.02") (r) nitto nt05/nt01 or toyo tq drag radials

I'm on saleen 18x9, 18x10.5's as well, good luck and post pics if you go for it.
 

c6zhombre

E85 NutSwinger
Established Member
Joined
Sep 14, 2008
Messages
5,430
Location
League City, TX
what size tire are you running in the rear? 26.74" sounds gigantic for the front (not to mention adding unsprung weight vs the 35)
 

99gtstinger

Member
Established Member
Joined
Jul 22, 2005
Messages
212
Location
Los Angeles
The 40 vs the 35 would only be a slight difference, for comparison the 2000 cobra r came factory with 265/40/18. that equates to 26.42" tall so you can look online and see if you like how those sit ( they were low ride height wise factory, pretty much as low as you can get that car.) 275/40/18's would be only slightly taller at 26.74" tall so its literally only a 1/2" difference over a cobra r setup. hope that helps for a reference .

the conversion formula is as follows: tread-width multiplied by sidewall as a percentage out of 100 (ie a 40 side wall would be 40% of the tread-width, a 70 would be 70% of the tread-width.). with that resulting number, divide it by 25.2 ( the number of millimeters in an inch). then multiply that number by 2 (top and bottom sections of the sidewall with the rim in between those areas of course) then add to that number the rim diameter in inches. so example:

275/40/17: 275*40%= 110. 110/25.2=4.37. (4.37*2)+17=25.74" or roughly 25 and 3/4" tall.

reference heights

-factory 03 cobra @ 275/40/17 = 25.74" ( 25 & 3/4")
-factory 00 cobra r @ 265/40/18 = 26.42" (26 & 1/2")
-your thoughts of a 275/40/18 = 26.74" (26 & 3/4") (roughly 1/2" taller sidewall above and below the rim. 1" taller altogether over your current setup)

all of these fit a mustang fine. do it, it'd look sick if you ask me. I am going to do a similar setup with ~26" (f) and ~27" (r)
(285/35/18) (25.92") (f) nt05s/nto1 nittos
(325/35/18) (27.02") (r) nitto nt05/nt01 or toyo tq drag radials

I'm on saleen 18x9, 18x10.5's as well, good luck and post pics if you go for it.

Great job explaining this. However, though not a big difference, there are 25.4mm in 1 inch. So you would divide by 25.4 instead of 25.2

OP, what size tires are you running in the back? You will want to avoid running a bigger overall diameter than the rears or else you may lose any raked look you have. By going up to that size, your car will be about .5" higher from the ground in the front....
 
Last edited:

tt335ci03cobra

Well-Known Member
Established Member
Joined
Feb 15, 2008
Messages
6,958
Location
USA
Oh jeez, that's right. My bad.

-275/40/17= 25 2/3" tall (stock 03 cobra)
-275/35/18= 25 9/16" tall (your current wheel size)
-265/40/18= 26 1/3" tall (stock 2000 cobra r, look online at pics as it's close)
-275/40/18= 26 2/3" tall (the size you were thinking of doing)
 

Bballplayanick

K1ng C0bRa
Established Member
Joined
May 18, 2008
Messages
856
Location
New York
I would also like to see some pictures. I plan on buying 18x9/10 black saleens and I am deciding which tire to go with. I plan to lower the car with H&R springs but sport springs like the OP so Im wondering if 275/40/18 will be too much and be hiding under the fender wall. Does anybody have any pictures of their cobra sitting on 18 inch saleens w/ XXX/35/18s?
 
Last edited:

BrettT 93|03

93 & 03 Cobra Venom
Established Member
Joined
Jun 15, 2004
Messages
428
Location
Maryland
Thanks for the info...

I think Im going to do the Steeda X2 balljoints first and see what happens.
Great info above and explanation. Thanks again.

I plan to do the X2's over the holidays. I post pics then.
 

gargstang

Member
Established Member
Joined
Apr 10, 2010
Messages
168
Location
Colorado
I don't have any pics available but I run the 275/40 18s on my Saleens and they are too tall. I rub in roughly the 2 o'clock area if you are looking at the driver's side wheel. Every time I hit a bump they rub on each side. I have Eibach Pros with both ISOs installed.
 

BrettT 93|03

93 & 03 Cobra Venom
Established Member
Joined
Jun 15, 2004
Messages
428
Location
Maryland
I don't have any pics available but I run the 275/40 18s on my Saleens and they are too tall. I rub in roughly the 2 o'clock area if you are looking at the driver's side wheel. Every time I hit a bump they rub on each side. I have Eibach Pros with both ISOs installed.

Thanks, never thought about rubbing if they would rub or not.
 

Teej281

Active Member
Established Member
Joined
Aug 6, 2007
Messages
2,010
Location
Hanover, PA
Well it will take up some of the wheel gap, but you will also add ride height which will be taking care of one issue and adding another. I think it would look not right personally. Keep the 275/35-18's on there.
 

Users who are viewing this thread



Top