Darrell O'Neill Posted April 23, 2006 Posted April 23, 2006 Ok, I know this topic has been done to death, but all I can drag up from the search is offset measurement methods etc... and not direct answers to my queries... So here goes.... I decided today to swop my front and rear wheels around (donuts have taken it's toll on the rear wheels ) Im pretty sure the front and rear wheels are different offset is this normal? The rear wheel will not fit the front and make contact with the wheel gaurds Im running Yoko 539's in 205/50R15 86V. The rear wheels have ET15 stamped on them but the fronts have this very long number stamped but I cannot make out the offset size 7015JZZ 35P 4108 72NP C592 KBA44039 1CC1BE72 050401 Can anyone tell me what offsett it is likely to be? 2001 SEIW 2LVX Also, Im possibibly looking to purchase 13inch wheels and rubber in the near future, could someone suggest the ideal offset for these? so that I will be able to swop fronts and rears? edited to say, there is some slight wear on the inner wall of the fronts from contact with the wings, so I feel my current offest is'nt ideal Quote
adhawkins Posted April 23, 2006 Posted April 23, 2006 Ok, I know this topic has been done to death, but all I can drag up from the search is offset measurement methods etc... So why not measure the wheels you have? Andy Quote
neilwillis Posted April 23, 2006 Posted April 23, 2006 Swap a front and back wheel over, see whether there's a difference. Mine are identical front and rear. Quote
adhawkins Posted April 23, 2006 Posted April 23, 2006 I decided today to swop my front and rear wheels around (donuts have taken it's toll on the rear wheels ) Im pretty sure the front and rear wheels are different offset is this normal? The rear wheel will not fit the front and make contact with the wheel gaurds He already has Andy Quote
jeff oakley Posted April 23, 2006 Posted April 23, 2006 The only way is to measure the wheel. I am pretty sure westfield recommend et38 however on my rear wheels I have had to use a hubcentric spacer to bring the wheels out into the wheel arch otherwise they looked crap. So by using a 25mm spacer on an et38 wheel you reduce it to it is effectivly an et13. HTH Jeff Quote
Darrell O'Neill Posted April 23, 2006 Author Posted April 23, 2006 Ok, I know this topic has been done to death, but all I can drag up from the search is offset measurement methods etc... So why not measure the wheels you have? Andy Guess I'll have to re-search, all I was turning up was have to measure the required offset. I reallly find this whole offset thingy confusing and was hoping there was a standard or universal accepted offset for my age chassis... Quote
Animal Posted April 23, 2006 Posted April 23, 2006 My wheels have a offset of 20mm and use a spacer of 20mm on the rear i can fit any wheel to any hub. IMHO the universal offset is 20mm Paul Quote
Blatman Posted April 23, 2006 Posted April 23, 2006 35P 4108 That part of the number looks like offset (35P, so ET35) and 4108 is 4 stud, 108PCD... IMHO of course... If the wheels with that number are fouling something on inner part of the wheel (what's a wheel guard?) then they are sitting further inboard than the wheels that came off which supports my theory. It is entirely possible that the guy who built your car has used different offsets front and rear. My green car has different offsets front and rear, but this is accomplished with spacers. 15mm on the rear, 6mm on the front, with all 4 wheels being ET37 offset. *IF* I'm right you'll need to add 20mm spacers to the front hub to match the ET15 wheels you want to fit on the rear. Further to the research/spec gathering I've been doing for my article on offsets, I have these measurements squirrelled away: Measured from the FLAT of the rim, NOT the outer edge, these measurements apply to 7" wide wheels *only* and are approximate because backspace measurement is NOT a 100% accurate method... ET37 wheels have a backspace of approximately 133mm. ET23 offset have a backspace of approximately 119mm and ET15 are approximately 111mm. Accuracy is +/- 3mm... Quote
stu999 Posted April 24, 2006 Posted April 24, 2006 Measured from the FLAT of the rim, NOT the outer edge, these measurements are approximate because backspace measurement is NOT a 100% accurate method... ET37 wheels have a backspace of approximately 133mm. ET23 offset have a backspace of approximately 119mm and ET15 are approximately 111mm. Accuracy is +/- 3mm... Err, wont the width of the rim also play a part with these backspace measurements? Quote
Blatman Posted April 24, 2006 Posted April 24, 2006 To a point, which is why I included the 3mm tolerance and stressed the approximate nature of the backspace measurements given. I actually found that measuring wheels from different manufacturers would indeed throw up anomalies like that. For example, a 15x7 OZ Superleggerra, ET37 has a 133mm backspace. A 13x7 K&N Minator ET23 has a backspace of 122mm, a difference of 11mm, when the offsets are actually 14mm different. I was trying to avoid too much confusion. This article is getting longer and longer all the time... Quote
stu999 Posted April 24, 2006 Posted April 24, 2006 To a point, which is why I included the 3mm tolerance and stressed the approximate nature of the backspace measurements given. I actually found that measuring wheels from different manufacturers would indeed throw up anomalies like that. For example, a 15x7 OZ Superleggerra, ET37 has a 133mm backspace. A 13x7 K&N Minator ET23 has a backspace of 122mm, a difference of 11mm, when the offsets are actually 14mm different. I was trying to avoid too much confusion. This article is getting longer and longer all the time... My point being is that before the tape measure even leaves the toolbox, there going to be approx 25mm difference between (for example) a 5.5 inch rim, and a 7.5 inch rim... Quote
Blatman Posted April 24, 2006 Posted April 24, 2006 You're right. I'll edit the post with the backspace measurements... Quote
Blatman Posted April 24, 2006 Posted April 24, 2006 Got me trawling the web now for more research... I found a pretty good offset calculator though Plenty of backspace numbers and lots of other good stuff here. Quote
Barry Ashcroft Posted April 24, 2006 Posted April 24, 2006 Blatters for your article I have 71/2 x 16 with a ET30 offset which fill the rear arches perfect Quote
Darrell O'Neill Posted May 8, 2006 Author Posted May 8, 2006 Urgent help please.... Assuming im currently running ET15 rears and ET35 fronts, Im about to order new rubber and wheels from polleymotorsport today..... 185/60/13 on a 13x6 rim They have two offsets in stock ET18 and ET24, my calculations are that ET18's will sit 2mm further outbound than my current rears and a 18mm spacer will match my current front position.... can someone confirm this.... could be a costly mistake otherwise... Quote
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