alloys offset question

[philg]

Right I'm starting to look out for some rims for the car, i fancy some 16" for the road.

I used to run 205 40 16s on a 7.5x16 but can not remember offset.

Question is does the offset stay the same the larger and wider the rims get? I know et35 is about right, does that apply to a 15" and 16" rim and what happens if you go from a 7x16 to a 7.5 by 16 does the et still stay the same with the wider rim.

I would imagine there would be a different et for a wider rim on the same size alloys, if you get my drift.

I really fancy some borbet a's which unfortunately come in a et20

Cam someone explain the maths behind it and advise me

phil

[clee]

It's all very straightforward but ...it depends how the width is quoted .
http://www.1010tires.com/WheelOffsetCalculator.asp

[firstchoicegary]

i had 195 40 16's not sure of offset etc but was fine no rubbing nothing

[philg]

i had 195 40 16's not sure of offset etc but was fine no rubbing nothing

how wide was the rim?

[Andrew Cooke]

ET35 will always put the tyre tread in the same place irrespective of rim width and diameter. ET20 will move the tyre tread 15mm outboard. It's more a question of what rubs where.

7" = 178mm
178/2 = 89mm
et 35 puts 89+35 = 124mm in from mounting face
and 89-35 = 54mm out from mounting face

7.5" = 190mm
190/2 = 95mm
et 20 puts 95+20 = 115mm in from mounting face
and 95-20 = 75mm out from mounting face

make any sense?

[firstchoicegary]

not sure 7,0 i think was oz superlegra

[Andrew Cooke]

not sure 7,0 i think was oz superlegra

yep, they'll be a 7

[firstchoicegary]

there you go at least someone knows

[philg]

ET35 will always put the tyre tread in the same place irrespective of rim width and diameter. ET20 will move the tyre tread 15mm outboard. It's more a question of what rubs where.

7" = 178mm
178/2 = 89mm
et 35 puts 89+35 = 124mm in from mounting face
and 89-35 = 54mm out from mounting face

7.5" = 190mm
178/2 = 95mm
et 20 puts 95+20 = 115mm in from mounting face
and 95-20 = 75mm out from mounting face

make any sense?

hell no

[clee]

typo on the second set of figures
190/2 =95

ET is the offset from the wheel width centerline

[philg]

so say you were buying 16 inch wheels, option 1 7" option 2 7.5" if you bought with the same et ie 35 for the gt, so on the 7.5" you would have 6ml extra rim on the inside of wheel and on the outside as opposed to the 7"

phil

[Andrew Cooke]

so say you were buying 16 inch wheels, option 1 7" option 2 7.5" if you bought with the same et ie 35 for the gt, so on the 7.5" you would have 6ml extra rim on the inside of wheel and on the outside as opposed to the 7"

phil

correct

[philg]

so if you had on 16s 7" wide et 35 and only had say 4 ml clearance to your strut, then a 7.5" wide wheel of the same et would rub, would you then get a different et of a smaller number say a 30 to get them on?

[firstchoicegary]

lost me phil . i think perfect for five is 195 40 16 and i had 7.0 wide wheels no point over strectching rubber unless a show car but not sure how well car would cope on road. what look you after and what purpose for car??

[philg]

i want these 16" but come in the wrong offset

[Andrew Cooke]

so if you had on 16s 7" wide et 35 and only had say 4 ml clearance to your strut, then a 7.5" wide wheel of the same et would rub, would you then get a different et of a smaller number say a 30 to get them on?

possibly, it depends where you measure the 4mm. If it was the rim that was close, then yes.

[Ashy]

i want these 16" but come in the wrong offset

Thats a nice 5, whos is it?

[blaze]

it all depends on the design of the alloy which will effect the et

use this http://www.alloywheels.com/

select your car and model an size of alloy you want to use and it will show u the alloy plus the et for that alloy as well

[firstchoicegary]

how come they on a five but you cant get them then???

[firstchoicegary]

ronals or borbets i think are amazing on a five or go williams 15's sprayed graphite grey

[philg]

how come they on a five but you cant get them then???

They are markey b's brothers car, he had to get the wheels machined to fit.


phil