Offset Revisited

[Auto-9]

I was reading up on the Acura forums and they said that when you go with wider rims, you also need to change which offset you require. For example my stock rims are 6 inches using the +46 offset, and if I want to go to 7.5 inches I'd have to buy a rim using about a +65 offset is how I understand it. Is this true or can I buy the 17x7.5 rims +42 offset rims I like without my wheels sticking out from under the car?

[Reelax]

you would only have to stray from the +46 measurement if the rims were very wide. our wheels wells are actually pretty big as is the clearance to our suspension. 7.5" +45 sits right in the middle of clearance from the rear fender and the suspension. if you go over 7mm offset in either direction from +46 (stock) w/ this width you will be in danger of rubbing. also if you go wider than 7.5, you will need to have an offset that would be more negative than +46 to push the rim away from the centerline of the car and the suspension to maintain clearance which would probably make you rub your fenders (you would have to roll them to get more clearance). since our stock rim is very undersized, you do not necessarily have to change offset from +46 if you want a rim wider than 6"... within reason of course. a 9" rim will not fit easily no matter what offest it is.

[99DE]

This is a good topic, because we usually discuss what offset, bolt pattern, and width to get but the stock offset is hard to find unless it is an 18'' and I want 17''. But, I haven't quite figured the science of offset and relationship to width until now. I've already noticed certain wheel manufactures change the offset of the same wheel from 15''-18'' and the offset does increase with the increase of the width. So, if everyone who has been saying get an 18'' wheel 7.5"w +45 offset you can move down to 17'' 7''width and 40-42 offset and still be centered just as an 18'' would. I think I got it figured. What do you think?

[BlankMan]

Actually, going to a 7.5" wide rim and keeping a 45mm offset pushes the wheel edge out another 1". But it's really not noticeable and , like reelax said, you can only go so far anyway before you will begin to rub. I found a nifty offset calc in Excel format a while back - forget where I found it - and I just put it online if you want to take a look at it (you have to d/l it first): Offset Wheel Width Calculator

Should clear things up. All credit to the original writer...

J

[Reelax]

<div class='quotetop'>QUOTE(99DE)</div><div class='quotemain'>This is a good topic, because we usually discuss what offset, bolt pattern, and width to get but the stock offset is hard to find unless it is an 18'' and I want 17''. But, I haven't quite figured the science of offset and relationship to width until now. I've already noticed certain wheel manufactures change the offset of the same wheel from 15''-18'' and the offset does increase with the increase of the width. Â*So, if everyone who has been saying get an 18'' wheel 7.5"w +45 offset you can move down to 17'' 7''width and 40-42 offset and still be centered just as an 18'' would. I think I got it figured. What do you think?</div>

well it wouldn't b "centered" between the suspension and fender but look at it this way. a 7" rim is a 1/4" thinner per side than a 7.5" rim. basically 1"=25mm. so a quarter inch is about 6mm. offset is the distance that the bolt plane is from the centerline of the rim; the more positive, the more the rim is inboard and the bolt plane is pushed out, the more negative the offset is, the more the more th bolt plane is inboard and the rim is pushed out. now the 17x7 +40 would b 6mm narrower per side but the rim itself would sitck out 5mm more than a 18x7.5 +45. the end result of the shift in the 2 dimensions is that the face of the wheel would be just about in the same place on both wheels (about 1mm diff -6mm+5mm)... but you would have more suspension clearance on the 17. both would sit pretty flush w/ the fender hole.

[Auto-9]

I see I see...so I should be ok with the 17x7.5 +42 wheels I'm looking to buy without it sticking out of the wheel well? Don't wanna look like the Civic and Accord rims gone wrong. Kinda want the wheels tucked under the outer fender edge but as long as it's flush like factory I'll be happy.

[Reelax]

I see I see...so I should be ok with the 17x7.5 +42 wheels I'm looking to buy without it sticking out of the wheel well? Don't wanna look like the Civic and Accord rims gone wrong. Kinda want the wheels tucked under the outer fender edge but as long as it's flush like factory I'll be happy.

7.5 +42 will stick out 3mm more than my rims (+45). 3mm is almost nothing. click on my sig to see pics.

225/45zr17 is the tire i reccomend for 17's but if you're worried about rubbing your tire go w/ 215/45zr17 and you should be fine.

[Xska55]

i could never under stand this whole concept of offset, honestly it drives me nuts,, I have 18x7.5 with a 40 offset. I remeber asking this guy from
norcal and he said 42 would be perfect,, does 2mm make a difference and
if not what is the perfect offset to keep it tucked under the fender,,, maybe i could get a positive answer once and for all,,,,

[Danger DANJ]

<div class='quotetop'>QUOTE(Rallifan)</div><div class='quotemain'>I see I see...so I should be ok with the 17x7.5 +42 wheels I'm looking to buy without it sticking out of the wheel well? Don't wanna look like the Civic and Accord rims gone wrong. Kinda want the wheels tucked under the outer fender edge but as long as it's flush like factory I'll be happy.</div>

I have 18" rims, but they are 7.5" wide with a +42mm offset. I'm dropped 1.8" in the rear and have a camber kit in the rear as well. The rear wheels line up almost flush with the edge of the fender, maybe a mm or so inside of it. I do get rubbing once in a while, but if you aren't dropped, you won't have any problems with the rims you want. Even if you do drop the rear close to what I have, you will still be fine if you don't put on a camber kit since the top of the wheels will be pointing inwards slightly. With the wheels you want, you should be good with 225/45/17" tires.

[TJC]

<div class='quotetop'>QUOTE(BlankMan)</div><div class='quotemain'>Actually, going to a 7.5" wide rim and keeping a 45mm offset pushes the wheel edge out another 1". Â*But it's really not noticeable and , like reelax said, you can only go so far anyway before you will begin to rub. Â*I found a nifty offset calc in Excel format a while back - forget where I found it - and I just put it online if you want to take a look at it (you have to d/l it first): Offset Wheel Width Calculator

Should clear things up. Â*All credit to the original writer...

J</div>

Glad you like my little spreadsheet; that was made by me. There was also a pretty good website that calculated how far the wheel actually stuck out too but can't find it right now.

I have my new 19 x 7.5 +40 and 225/35/19 tires and they just about flush with the edge of the fender. No drop but looks good (contrary to everyones belief about that monster truck look). I think the main reason is because the wheel is so big to begin with that the gap doesn't look bad.