Discussion
hi all just after some advice currently got staggered m6 alloys on my e36 m3, rears are 9j et 43 & fronts are 8j et 40. the rears look immense and i used 3mm spacers on the fronts to push them out even more. i dont really know what the j means? Im looking at new set of alloys which are 9.5j et 40 rears & 8.5j et 40 fronts. will they look simmilar in stance wise fitted as my alloys on now or sit in more
thanks for any advice
thanks for any advice
How technical are you when it comes to wheel engineering and mathematics?
Simply most wheels for cars today have a J stamped on them regardless of width, style and manufacturer. This letter refers to a complex equation to do with the flange and measurements of where the tyre beading meets the wheel...ie rim contour.
Tyre fitters will know more, but this letter is an industry code which enables tyre fitters to fit the right tyres the the wheels to stop rim slippage and tyres flying off wheels once mounted.
Simply most wheels for cars today have a J stamped on them regardless of width, style and manufacturer. This letter refers to a complex equation to do with the flange and measurements of where the tyre beading meets the wheel...ie rim contour.
Tyre fitters will know more, but this letter is an industry code which enables tyre fitters to fit the right tyres the the wheels to stop rim slippage and tyres flying off wheels once mounted.
J refers to the width of the wheel, and ET the offset. Offset is important as it determines how much the wheels sit out from the hub.
Your existing front wheel are 8 inches with an ET of 40 reduced to 37 with your spacers. Your new front wheels are 8.5 inches, therefore all other things being equal, they will stick out by a further 1/4 inch, being half of 8 less 8.5. Given the offsets of both wheels are the same, the new wheels will stick out about 3mm more than your existing set up with spacers. Therefore no need for the spacers.
The rear wheel position is a bit more complicated. The wider width of the wheel (1/2 inch) means that all things being equal the new wheel would stick out more by 1/4 inch ie, 6.25mm. However, the difference in offset of 3mm, also makes the wheel stick out by 3mm. Therefore the new wheel will sit nearly 1cm further out than the old rear wheel.
Pretty sure my calcs are right but happy to be corrected.
If they are correct, make sure you have the necessary clearance inside the wheel arch to accommodate the wider wheels.
Your existing front wheel are 8 inches with an ET of 40 reduced to 37 with your spacers. Your new front wheels are 8.5 inches, therefore all other things being equal, they will stick out by a further 1/4 inch, being half of 8 less 8.5. Given the offsets of both wheels are the same, the new wheels will stick out about 3mm more than your existing set up with spacers. Therefore no need for the spacers.
The rear wheel position is a bit more complicated. The wider width of the wheel (1/2 inch) means that all things being equal the new wheel would stick out more by 1/4 inch ie, 6.25mm. However, the difference in offset of 3mm, also makes the wheel stick out by 3mm. Therefore the new wheel will sit nearly 1cm further out than the old rear wheel.
Pretty sure my calcs are right but happy to be corrected.
If they are correct, make sure you have the necessary clearance inside the wheel arch to accommodate the wider wheels.
Alpinestars said:
J refers to the width of the wheel, and ET the offset. Offset is important as it determines how much the wheels sit out from the hub.
Your existing front wheel are 8 inches with an ET of 40 reduced to 37 with your spacers. Your new front wheels are 8.5 inches, therefore all other things being equal, they will stick out by a further 1/4 inch, being half of 8 less 8.5. Given the offsets of both wheels are the same, the new wheels will stick out about 3mm more than your existing set up with spacers. Therefore no need for the spacers.
The rear wheel position is a bit more complicated. The wider width of the wheel (1/2 inch) means that all things being equal the new wheel would stick out more by 1/4 inch ie, 6.25mm. However, the difference in offset of 3mm, also makes the wheel stick out by 3mm. Therefore the new wheel will sit nearly 1cm further out than the old rear wheel.
Pretty sure my calcs are right but happy to be corrected.
If they are correct, make sure you have the necessary clearance inside the wheel arch to accommodate the wider wheels.
very informative, that's what i was after. but i thought the higher the offset the further they stick out. the fronts are ET40, i thought adding 3mm spacers would make it 43mm as the rears are ET 43 and still stick out a litle more Your existing front wheel are 8 inches with an ET of 40 reduced to 37 with your spacers. Your new front wheels are 8.5 inches, therefore all other things being equal, they will stick out by a further 1/4 inch, being half of 8 less 8.5. Given the offsets of both wheels are the same, the new wheels will stick out about 3mm more than your existing set up with spacers. Therefore no need for the spacers.
The rear wheel position is a bit more complicated. The wider width of the wheel (1/2 inch) means that all things being equal the new wheel would stick out more by 1/4 inch ie, 6.25mm. However, the difference in offset of 3mm, also makes the wheel stick out by 3mm. Therefore the new wheel will sit nearly 1cm further out than the old rear wheel.
Pretty sure my calcs are right but happy to be corrected.
If they are correct, make sure you have the necessary clearance inside the wheel arch to accommodate the wider wheels.
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