How much more clearance do I get from this tire size?

[s3cf]

So currently I m running

235/40/18 (F) (9.5" wheel width)
245/40/18 (R) (10.5" wheel width)

with those size my tires still rub the fender so I think I need something smaller

so I was thinking

215/40/18 (F)
225/40/18 (R)

Questions
1) what is the actual additional clearance (from the fender) do I get if I switch to the smaller size? Is it simply (235 - 215 ) / 2 = 10mm ?

2) Should I get 35 or 40 profile if I want more clearance?


Thanks in advance

[Schultz28]

what kind of car are these going on and what is the offset of the wheels?

not to mention you can fix rubbing by adding some more camber....

[MrZog]

Questions
1) what is the actual additional clearance (from the fender) do I get if I switch to the smaller size? Is it simply (235 - 215 ) / 2 = 10mm ?

well . . yes (also depends of the tire, there are variations in width even in the same size in differend brands and types . .) . . but also you get more "clearance" because "40" isn't a fixed size, it's the "hight" of the sidewall in percentage of the with of the tire . . so the overall diameter of a 235/40R18 is 64.5cm . . while the 215/40R18 is only 62.9cm . . a 215/35R18 is 60.8cm . .

right now, with your current sizes, you have different overall diameters . . I would recommend a wider tire on the rear rim, otherwise you have a lot of stretch on the rear and less on the front . . not sure if that looks good . . . maybe 215/40 in the front and 235/35 in the rear . . so the diameters are very close .

[s3cf]

what kind of car are these going on and what is the offset of the wheels?

not to mention you can fix rubbing by adding some more camber....

Thanks for your response.
offset is +15 (R) and +12(F)
car is a LS400

I think i had maxed out the camber with stock components. (R: ~ -4.5, F: ~ -2.5)

[s3cf]

well . . yes (also depends of the tire, there are variations in width even in the same size in differend brands and types . .) . . but also you get more "clearance" because "40" isn't a fixed size, it's the "hight" of the sidewall in percentage of the with of the tire . . so the overall diameter of a 235/40R18 is 64.5cm . . while the 215/40R18 is only 62.9cm . . a 215/35R18 is 60.8cm . .

right now, with your current sizes, you have different overall diameters . . I would recommend a wider tire on the rear rim, otherwise you have a lot of stretch on the rear and less on the front . . not sure if that looks good . . . maybe 215/40 in the front and 235/35 in the rear . . so the diameters are very close .

thanks for your input, that really helps!

[s3cf]

well . . yes (also depends of the tire, there are variations in width even in the same size in differend brands and types . .) . . but also you get more "clearance" because "40" isn't a fixed size, it's the "hight" of the sidewall in percentage of the with of the tire . . so the overall diameter of a 235/40R18 is 64.5cm . . while the 215/40R18 is only 62.9cm . . a 215/35R18 is 60.8cm . .

right now, with your current sizes, you have different overall diameters . . I would recommend a wider tire on the rear rim, otherwise you have a lot of stretch on the rear and less on the front . . not sure if that looks good . . . maybe 215/40 in the front and 235/35 in the rear . . so the diameters are very close .

by the way my current tires are Nangkang NSii, so for the new size should i stay with NSii or i should go with falken for better stretchability?
thanks