stevechumo

iTrader: (5)

I'm currently running 245/40/18 tires for the front and the rear on my SC400. I'm thinking to change the rear tires using the same rims to 255/40/18 to gain some traction and a wider look. I'm also considering to go to fatter tires of 265/40/18.

So I don't know if the 265/40 tires will fit and look nicer than the 255/40 or the 245/40. Will the 255/40 give an exact additional 5 mm on each side wall? Or will the 265/40 give an exact additional 10 mm on each side wall? Can anyone give me some opinions?

I wish that I can afford to change to the complete 245/35/19 for the front and 275/35/19 for the rear, but I don't want to waste my current 245/40/18 rim set.

Any info. is greatly appreciated.

mitsuguy

iTrader: (2)

what size wheels do you have???

275/35-18 would actually be the more appropriate size for the car as it would be the same sidewall height as what you have, but over an inch wider... now, if you have narrowish wheels, then I would just stay where you are until you can afford to do what you want...

and if you did 19's, you would want 275/30-19 as this would be the correct height...

stevechumo

iTrader: (5)

I'm not so sure about the rim width, perhaps it's 8.5". The 245/40 tire just covers enough and about 4-5 mm outside of the rim's both sides to protect it against scratches..etc. I'm afraid the 275/../18 is too large for the rims and .../35/18 is too thin/small for the whole wheel diameter. I think .../35/.. is more suitable for 19" rim.

mitsuguy

iTrader: (2)

the 35 series is a percentage...

245/40-18, 40% of 245 = 98mm sidewall height

275/35-18, 35% of 275 = 96.25mm sidewall height

a difference of only 1.75 mm with a tape measure, it wouldn't even be measurable difference... 275's would be best on a 9" or wider wheel...

I'd still stay with what you have until you are ready to do it right...

stevechumo

iTrader: (5)

Thanks, Cody. Since you're an expert in tires & wheels, I can't argue with you more. So what would be your suggestion for the best of my current rear tire? I really need to gain a few millimeters on both sides and I don't want to stay with the current rear tire.

mitsuguy

iTrader: (2)

if you must absolutely have something wider, I'd do 265/40-18... this will be 10mm wider on either side, should work with everything just fine, but keep in mind, it will be a little more than a half inch taller... 275/35-18 would probably look not so good on those wheels, and would bulge out a lot, whereas the 265/40-18 will bulge a bit, but because of the taller sidewall, not look as bad...

stevechumo

iTrader: (5)

Thanks for your tips, Cody. I'll carefully look into the tires before I make the decision. I don't want to increase the tire height in any way.

mitsuguy

iTrader: (2)

the only thing that will *work* on your wheels that will be the same height is 275/35-18 then... it might just bulge out the sidewall a bit, depending on how wide your wheels really are...

TXFM

Here are 2 websites that might be helpful:

This one shows the differences in tire dimensions: http://www.discounttire.com/dtcs/infoTireMath.dos

This one is a Wheel Offset Calculator: http://www.1010tires.com/WheelOffsetCalculator.asp

stevechumo

iTrader: (5)

Cody,
This is an old thread but do you think 265/35/18 would give me the same height as the 245/40/18? Thanks.

sleeper408

iTrader: (6)

265/35 = 92.75 mm sidewall height
245/40 = 98 mm sidewall height

mitsuguy

iTrader: (2)

yup,so, overall a little bit shorter diameter, almost half an inch...

but it would work...

stevechumo

iTrader: (5)

So comparing with 255/40/18, does 265/35/18 look better or worse?

mitsuguy

iTrader: (2)

up to you... 255/40-18 is a little taller, but it kinda depends on the wheel, and what you are looking for....

stevechumo

iTrader: (5)

Thanks. The reason is I'm currently running 245/40/18 in the front, and looking to have just a little bit more traction for the rear (I'm building a turbo system) and without a ridiculous unmatched look for the front & rear.

I don't know who'll buy my 18" rims, otherwise, I'll go with 245/35/19 front & 275/30/19 rear. And if just putting them aside is a big waste.