Wheel Offset question
15 May 2009, 11:57 AM
#1
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Wheel Offset question
I have the sti alloys to clear the brembo's at the front, going to order some new wheels shortly and need to know what offset I need.
I have read the current have 53
The ones I am looking at are 42, but the ad states they will clear Brembos
Can anyone expert with wheels (STU
) help
I have read the current have 53
The ones I am looking at are 42, but the ad states they will clear Brembos
Can anyone expert with wheels (STU
) help
15 May 2009, 12:17 PM
#4
offset is soemthing to do with the distance the outside of the rim is from the hub i think. pretty sure a bit more than offset will also effect if the wheels clear brembos too.
If the advert says they clear David then i'd be tempted to get them ordered and give them a go
If the advert says they clear David then i'd be tempted to get them ordered and give them a go
15 May 2009, 12:19 PM
#5
I was along the right lines. taken from wiki
The offset of a vehicle's wheel is the distance between the centerline of the wheel and the plane of the hub-mounting surface of the wheel. It can thus be either positive or negative, and is typically measured in millimeters. Offset has a significant effect on many elements of a vehicle's suspension, including suspension geometry, clearance between the tire and suspension elements, the scrub radius of the steering system, and visually, the width of the wheel faces relative to the car's bodywork.
Zero Offset - The plane of the hub mounting surface is even with the centerline of the wheel.
Positive Offset - The plane of the hub mounting surface is shifted from the centerline toward the front or outside of the wheel. Positive offset wheels are generally found on front wheel drive cars and newer rear drive cars.
Negative Offset - The plane of the hub mounting surface is toward the back or brake side of the wheel's centerline.
"Deep dish" wheels typically have negative offset or a very low positive offset.
To maintain handling characteristics and avoid undue loads on bushings and ball joints, the car manufacturer's original offset should be maintained when choosing new wheels unless there are overriding clearance issues.
Wheels are usually stamped with their offset using the German prefix "ET", meaning "Einpresstiefe" or, literally, "insertion depth". An example would be "ET45" for a 45mm offset.
Calculating the offset of a wheel is a fairly easy mathematical equation. First, measure the overall width of the wheel (remember, just because a wheel is 18x7.5, does not mean that the OVERALL width is 7.5”. It means that the measurement between the outboard flange and the inboard flange is 7.5”). Next, divide that width of the wheel by two; this will give you the centerline of the wheel.
Overall width/2 = Centerline
After determining the centerline, measure from the hub-mounting surface of the hub to the edge of the inboard flange (if the wheel were laying flat on the ground – face up – your measurement would be from the ground to the hub-mounting surface). This is your back spacing.
Back spacing - Centerline = Offset
The offset of a vehicle's wheel is the distance between the centerline of the wheel and the plane of the hub-mounting surface of the wheel. It can thus be either positive or negative, and is typically measured in millimeters. Offset has a significant effect on many elements of a vehicle's suspension, including suspension geometry, clearance between the tire and suspension elements, the scrub radius of the steering system, and visually, the width of the wheel faces relative to the car's bodywork.
Zero Offset - The plane of the hub mounting surface is even with the centerline of the wheel.
Positive Offset - The plane of the hub mounting surface is shifted from the centerline toward the front or outside of the wheel. Positive offset wheels are generally found on front wheel drive cars and newer rear drive cars.
Negative Offset - The plane of the hub mounting surface is toward the back or brake side of the wheel's centerline.
"Deep dish" wheels typically have negative offset or a very low positive offset.
To maintain handling characteristics and avoid undue loads on bushings and ball joints, the car manufacturer's original offset should be maintained when choosing new wheels unless there are overriding clearance issues.
Wheels are usually stamped with their offset using the German prefix "ET", meaning "Einpresstiefe" or, literally, "insertion depth". An example would be "ET45" for a 45mm offset.
Calculating the offset of a wheel is a fairly easy mathematical equation. First, measure the overall width of the wheel (remember, just because a wheel is 18x7.5, does not mean that the OVERALL width is 7.5”. It means that the measurement between the outboard flange and the inboard flange is 7.5”). Next, divide that width of the wheel by two; this will give you the centerline of the wheel.
Overall width/2 = Centerline
After determining the centerline, measure from the hub-mounting surface of the hub to the edge of the inboard flange (if the wheel were laying flat on the ground – face up – your measurement would be from the ground to the hub-mounting surface). This is your back spacing.
Back spacing - Centerline = Offset
15 May 2009, 12:19 PM
#6
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Pity there isn't a place near that stocks inovit alloys
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15 May 2009, 12:39 PM
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dont forget dave that the look of the car can be dramatically changed
by mixing the rim size and the offsets about
a bigger offset will give you the usa look
but beware not to come out to far that the tread pattern is
sticking out from the arches
my rays are 18x8.5 et35 and clear the ap's
see pics for the effect
an 18x9 et35 would stick out 1/4 inch more
but same as 18x8.5 et30
as the offset reduces the wheel edge moves outwards
so from et53 to et42 will move the wheel out 11mm
AFAIK hope that helps
by mixing the rim size and the offsets about
a bigger offset will give you the usa look
but beware not to come out to far that the tread pattern is
sticking out from the arches
my rays are 18x8.5 et35 and clear the ap's
see pics for the effect
an 18x9 et35 would stick out 1/4 inch more
but same as 18x8.5 et30
as the offset reduces the wheel edge moves outwards
so from et53 to et42 will move the wheel out 11mm
AFAIK hope that helps
15 May 2009, 01:13 PM
#11
Dave, high number sucked in look, low number sticky out look.
Brembo clearance is more about spoke design than offset as the STi wheels are 53 and my rotas are 48 and the clearance is greater on my STi rims. Both 17x7.5.
General rule from the wheels that I have tried is go for 18x8" with an ET48. Use 225 tyres as a minimum but ideally 235. If you go go 225 then go for a chunky tyre like the sessantas or Goodyears which afford rim protection like you were riding 235's in say a thinner fitting tyre like the T1R's.
ET42 is a bit low tbh, depending on the width of the rim and the tyre you want to run it may present problems, if not in rubbing then perhaps in hub/bearing wear ?
Some of the cheaper wheels I have seen offer a lot in 18x7.5 ET45 which I think would be ok.
What wheels are you after ? I have been known to strike a deal or two
Brembo clearance is more about spoke design than offset as the STi wheels are 53 and my rotas are 48 and the clearance is greater on my STi rims. Both 17x7.5.
General rule from the wheels that I have tried is go for 18x8" with an ET48. Use 225 tyres as a minimum but ideally 235. If you go go 225 then go for a chunky tyre like the sessantas or Goodyears which afford rim protection like you were riding 235's in say a thinner fitting tyre like the T1R's.
ET42 is a bit low tbh, depending on the width of the rim and the tyre you want to run it may present problems, if not in rubbing then perhaps in hub/bearing wear ?
Some of the cheaper wheels I have seen offer a lot in 18x7.5 ET45 which I think would be ok.
What wheels are you after ? I have been known to strike a deal or two
15 May 2009, 01:25 PM
#12
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Dave, high number sucked in look, low number sticky out look.
Brembo clearance is more about spoke design than offset as the STi wheels are 53 and my rotas are 48 and the clearance is greater on my STi rims. Both 17x7.5.
General rule from the wheels that I have tried is go for 18x8" with an ET48. Use 225 tyres as a minimum but ideally 235. If you go go 225 then go for a chunky tyre like the sessantas or Goodyears which afford rim protection like you were riding 235's in say a thinner fitting tyre like the T1R's.
ET42 is a bit low tbh, depending on the width of the rim and the tyre you want to run it may present problems, if not in rubbing then perhaps in hub/bearing wear ?
Some of the cheaper wheels I have seen offer a lot in 18x7.5 ET45 which I think would be ok.
What wheels are you after ? I have been known to strike a deal or two
Brembo clearance is more about spoke design than offset as the STi wheels are 53 and my rotas are 48 and the clearance is greater on my STi rims. Both 17x7.5.
General rule from the wheels that I have tried is go for 18x8" with an ET48. Use 225 tyres as a minimum but ideally 235. If you go go 225 then go for a chunky tyre like the sessantas or Goodyears which afford rim protection like you were riding 235's in say a thinner fitting tyre like the T1R's.
ET42 is a bit low tbh, depending on the width of the rim and the tyre you want to run it may present problems, if not in rubbing then perhaps in hub/bearing wear ?
Some of the cheaper wheels I have seen offer a lot in 18x7.5 ET45 which I think would be ok.
What wheels are you after ? I have been known to strike a deal or two
Inovit Torque Gunmetal - Alloy Wheels - Specialist supplier of alloy wheels and tyres packages, 0% Finance and Fast Delivery, Buy Online
In a 17" so I can just stick my current tyres on.
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