PDA

View Full Version : Widest tire for 18x8



ba83
06-18-2007, 01:27 PM
I just bought a Set of 18x8 40+ offset and I m actually looking to buy some tires,
I know that 245-40-18 is safe on all 4 corners
I was wondering If I could use 245-40-18 up front and get wider tires in the back , so what is the widest tire for the back on a 18x8 , I was thinking 265-35-18 but I m not sure, I would like to know if anyone has done that with an 8 inch wide wheel and any issues with the setup,



ecetim
06-18-2007, 02:01 PM
I was interested in the guidelines for this as well and did some googling.

TireRack has a long and involved article about it, which I didn't bother to read:
http://www.tirerack.com/tires/tiretech/tirespecske y.jsp

However national tire has a rule of thumb:
http://www.nationaltire.com/basics/default.asp
"Wheel Width
Distance between inside of flanges rounded to nearest 1/2-inch. Ensure that wheel width is proper for tire size you intend to mount on it. All tire sizes have minimum and maximum wheel width limits. Correct wheel width is about 75% of tire cross section width."

So an 8" wheel is ~203mm. Figure if the width should be 75% of the tire cross section, that leaves you with ~253mm of tire width. So technically you could run a 255 okay, 245 is safer.

I'm sure there will be people on here who will say 265's & 275's work fine, but in the end I think you are stressing more of the tire and opening yourself to trouble.

My $0.02
silvergto05
06-18-2007, 02:12 PM
i was thinking of doing the same thanks for the links
MVDCGTO
06-18-2007, 03:28 PM
I was interested in the guidelines for this as well and did some googling.

TireRack has a long and involved article about it, which I didn't bother to read:
http://www.tirerack.com/tires/tiretech/tirespecske y.jsp

However national tire has a rule of thumb:
http://www.nationaltire.com/basics/default.asp
"Wheel Width
Distance between inside of flanges rounded to nearest 1/2-inch. Ensure that wheel width is proper for tire size you intend to mount on it. All tire sizes have minimum and maximum wheel width limits. Correct wheel width is about 75% of tire cross section width."

So an 8" wheel is ~203mm. Figure if the width should be 75% of the tire cross section, that leaves you with ~253mm of tire width. So technically you could run a 255 okay, 245 is safer.

I'm sure there will be people on here who will say 265's & 275's work fine, but in the end I think you are stressing more of the tire and opening yourself to trouble.

My $0.02

I think your math is a bit off.

8x 25.4 (# of mm in one inch) = 203.2 mm
203.2mm / 0.75 = 270.93333333 mm

So technically a 265 should fit and be safe, a 275 is technically 4mm too wide but should be ok. That is going by the premise that a rim only need be 75% of the tire width.
ecetim
06-18-2007, 03:43 PM
Yeah you're right, oops!
LS2-GTO
06-18-2007, 03:50 PM
Heres a 275/35/18 on an 18x8:
http://www.ls2gto.com/forums/attachment.php?attach mentid=60414&stc=1&d=1181953263

and a 235/40/18 on an 18x8, same tires (Kumho MX's).
http://www.jhbi.com/gto/vz_left.jpg
ba83
06-18-2007, 07:08 PM
that looks nice, so I guess 275-35-18 , Hmmm,
Oh yea, any Rubbing under hard acceleration or any issues
ecetim
06-18-2007, 07:15 PM
Measure the contact patch between the two tires
ba83
06-19-2007, 10:31 PM
any uneven wear or installation issues with the 275s
slammin86
06-20-2007, 03:02 PM
This is a very interesting thread. I would love to see some more feedback.
trbo_blu
06-20-2007, 05:15 PM
I just ordered BF Goodrich KDW NT 255/35-18s and plan on running them on the stock rims for rear only. I'll post some feedback in a few days...they are coming from California.
slammin86
06-20-2007, 05:19 PM
I just ordered BF Goodrich KDW NT 255/35-18s and plan on running them on the stock rims for rear only. I'll post some feedback in a few days...they are coming from California.


Why did you choose 255 35 18 over 255 40 18?
ba83
06-20-2007, 08:40 PM
I m debating 265-35-18 or 275-35-18 , about to pull the trigger or 245 all round ( to be safe)
ecetim
06-21-2007, 04:07 AM
I say do 245's on an 8 inch wheel and just spend your money on a set of good tires. Quality > Quantity
Bad05GTO
06-21-2007, 06:38 AM
I have factory OEM 18's. Aren't they 18x8 as well? So will a 275 tire work on a daily driver with drag bags?
LS2-GTO
06-21-2007, 10:12 AM
I have factory OEM 18's. Aren't they 18x8 as well? So will a 275 tire work on a daily driver with drag bags?

If your rear cradle alignment is good and your fender lips are cut you wont need drag bags.

Just don't go throwing the car into a corner at over 100mph and it wont rub :drink: or peel the tires off the rim.
Bad05GTO
06-21-2007, 10:35 AM
If your rear cradle alignment is good and your fender lips are cut you wont need drag bags.

Just don't go throwing the car into a corner at over 100mph and it wont rub :drink: or peel the tires off the rim.

Lol, that won't be happening. I pretty much baby it to and from work everyday, and the abuse happens at the track. I was going to do the drag bags anyway to help with launching. I just need to find a good 275 tire...