More sidewall

[critter]

I have 255/35/18 KDW2 tires on the front of my car and would like to have more sidewall on thoses front tires. How much do I gain by going to a 40 aspect ratio?

[MCMLXIX]

go here: click on SPECS tab...
http://www.tirerack.com/tires/tires....ce+T%2FA+KDW+2

looks about 1" total diameter so maybe 1/2" taller....

[FatfreeGTO]

This is off the top of my head but I think the math is right.

255/35/18 means 255mm wide tread / 35% sidewall of your tread / in an 18 wheel

Take your 255mm (treadwidth in mm) divide by 25.6 (converts mm to inches) 255/25.6 = 9.96" of tread width
9.96" x .35 (35% of treadwidth) 9.96 x .35= 3.486" of side wall your 40 series will equal 9.96 x .40 =3.984" of sidewall. So yes MCMLXIX its a 1/2" taller sidewall. Hope this helps.

[MonzaRacer]

235/35/18 section width 9.3 shoulder height 3.2 OD 24.5
235/40/18 section width 9.3 shoulder height 3.7 OD 25.4
235/45/18 " " 9.3 " " 4.2 OD 26.3
235/50/18 " " 9.3 " " 4.6 OD 27.3
Now dont forget taller tire=larger foot print also. Added a few extra sizes for your use.

[critter]

You folks are great. Thanks for the help.

[LSx_88_Ciera]

This is off the top of my head but I think the math is right.

255/35/18 means 255mm wide tread / 35% sidewall of your tread / in an 18 wheel

Take your 255mm (treadwidth in mm) divide by 25.6 (converts mm to inches) 255/25.6 = 9.96" of tread width
9.96" x .35 (35% of treadwidth) 9.96 x .35= 3.486" of side wall your 40 series will equal 9.96 x .40 =3.984" of sidewall. So yes MCMLXIX its a 1/2" taller sidewall. Hope this helps.

Everything is correct other than 1" is 25.4mm not 25.6.

[buickfunnycar.com]

compare here too as well...

http://www.1010tires.com/tiresizecalculator.asp

[FatfreeGTO]

Everything is correct other than 1" is 25.4mm not 25.6.

Ahh damn I was close and it was late

[AintQik]

I always use this one.

http://www.miata.net/garage/tirecalc.html

[Samckitt]

The middle number is the number used for the sidwall height calculation. The sidewall height is figured by using this as a percentage of cross sectional width. For example, 255 width, 255X35% is the sidewall width.

255X35%=89.25mm or 3.5"
255X40%=102mm or 4"

[DriverzInc]

The middle number is the number used for the sidwall height calculation. The sidewall height is figured by using this as a percentage of cross sectional width. For example, 255 width, 255X35% is the sidewall width.

255X35%=89.25mm or 3.5"
255X40%=102mm or 4"

Exactly right!