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YOUR RESEARCHWheel offset and sizing help for 987?
Leading reported evidence
Run some junky 5mm ebay spacers
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Gotcha… I ran some junky 5mm eBay spacers on my MR2 decades ago and they were still fine.
Check twice" and "buy once" was definitely in order here
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Suggestion
As spacers aren't cheap, let alone incorrect measurements can cause car damage and most importantly -- potentially compromising everyone's safety -- I figured a "check twice" and "buy once" was definitely in order here.
Leading evidence: 'Run some junky 5mm ebay spacers' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'clearly understanding how offset works and actual clearance' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check twice" and "buy once" was definitely in order here' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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I’ve ran spacers on at least 15 cars and never had issues… anyway GL
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I am running stock suspension with 19 inch wheels.
clearly understanding how offset works and actual clearance
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I think part of the issue was my clearly understanding how offset works and actual clearance.
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than mine… +25 is probably a little extreme but it’ll work.
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
Check twice" and "buy once" was definitely in order here
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Suggestion
As spacers aren't cheap, let alone incorrect measurements can cause car damage and most importantly -- potentially compromising everyone's safety -- I figured a "check twice" and "buy once" was definitely in order here.
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Hi gang,
Although it is a bit late in the winter season, I'm still keeping my eyes peeled for winter rims for my new-to-me
987.2
.
Boxster base
. I had snow
tires
on my
987.1
and loved them.
However, I'm a bit confused per options per offsets and calculations. Stock for a 2010
987.2
is:
8J-18 ET57 (front)
9J-18 ET43 (rear)
I may have found an affordable set (I'm guessing off a 993?) that is the following:
7.5J-18 ET50 (front)
9J-18 ET52 (rear)
Tire sizes are an exact size match for the 987, so I'm guessing that someone made this work -- and I'm waiting to hear back from the seller. So, it seems like these might fit -- assuming I mount some sort of spacers on the rear. Anyone here facile with offsets and wheel spacer math? I just don't want to screw this up -- and buy these not knowing if they'll fit or not. Cheers and thanks.
Thanks,
@jdavis8361
-- Neat site, and I did check it out. Wasn't clear though -- as they're calling for a lot of 10" rears and these would be 9".
I'm hoping that the calculated offset difference would be -9 (I think?) and as the wheel widths are the same, maybe I'd just need to mount 10mm spacers and I'd be all set?
Well my 8.5 fronts are +49 w/ 245, so your good there… your an inch narrower (.5” per
Side) and only 1-2mm difference in offset…
I use to have 18x10 +41 and the 993 rears would be .5” less on each side, but you added +10mm of offset which moves it inwards 10mm, minus the .5” on each side.
you’ll probably only run a 255 rear on a 9”… maybe for appearance you can add +15 to 20mm spacer for a flusher look… follow?
A 10mm spacer with the appropriate lug bolts for the rear is all you need. Your sizing for the
987.2
is exactly the same as the
987.1
S that is J8 x 57 x18 f and J9 x 9 x 18 r. so your new fronts will be a little more outboard while the rears with the spacers will be the OEM dept. The trick to get both to match up when looking down the side of the car. To match these wheels up so they have the same off set from the OEM spects you will need about a 15 mm rear spacer. The actual math looks like this 57- 50 = 7, meaning the front is pushed out 7 mm. To line up the rear 52-43=9 plus 7 to match the outward offset in front out be 16mm Not sure that size spacer is available but 15mm certainly is. So do nothing in front, and 15mm in the rear. I've run 15mm f and 23mm spacers on the rear OEM wheels. So your new wheel set will not be as aggressive as mine front or rear.
Yup! Agree^… isn’t that what I said? 🤣 I was going to go back and type the equation but I fell asleep 💤
ya him and I like things nice and flush… looks mean that way
This is so cool, guys. I think I get it. Going to go make some coffee and break out my yellow legal tablet -- as you guys are great wheel math teachers. A huge thanks to you both.
You might find a calculator like this one useful. It provides a nice visual after you fill in the numbers.
Wheel Offset Calculator
Use our wheel offset calculator to visualize the new tire position when changing wheel and tire sizes. Convert wheel offset and backspacing to calculate the correct setup for your vehicle.
tiresize.com
Thanks! In fact, I just checked that website out earlier this morning. I think part of the issue was my clearly understanding how offset works and actual clearance. I haven't yet found a super-clear video or website that gives clear examples to work backwards from (or at least works with how my brain processes math problems).
As spacers aren't cheap, let alone incorrect measurements can cause car damage and most importantly -- potentially compromising everyone's safety -- I figured a "check twice" and "buy once" was definitely in order here. So, a huge thanks again!
If your referring to spacers not being safe.. buy quality pieces (ex: ECS or H&R) and per 1mm thickness of spacer you need 1mm longer studs.. if you just need the rears, shouldn’t cost more than 100-ish. I’ve ran spacers on at least 15 cars and never had issues… anyway GL
Oh, I just meant safe as in -- if I put the wrong wheels/
tires
on the car, it might be unsafe. Good to know about making sure I should buy a quality set.
Need help fitting a lobster claw wheel set front and rear in a
2011 Boxster S
. Wheel size are
Front 8x19 ET57
Rear 11x19 ET67
Note: I would like to have fender flush fitment in front and rear. Thanks a lot for your help
Sent from my
iPhone
using Tapatalk
Flush with those sizes should be around +42
For the 11’s
…
and 8’s +46 to around +40 depending on ride height, camber and tire size.
you probably need +25 spacer in the rear and fronts +15 up front. I’ll find the calculator
* also I just realized this is a
boxster
and I’m not sure if the fenders are different from the
cayman
…
Here is the offset calculator I used.
Here is the offset calculator I used. It works great.
Wheel Offset Calculator
Use our wheel offset calculator to visualize the new tire position when changing wheel and tire sizes. Convert wheel offset and backspacing to calculate the correct setup for your vehicle.
tiresize.com
I have a 987.2 as well, but mine is a Cayman. One would think they would be the same as a Boxster, but I don't know that for certain.
In any case, on the stock wheels, the offsets are 57 for front and 43 for rear. So the front looks fine, and as Porsche08 mentioned, you might use spacers to get a more flush effect. On the rear, the 25 spacer looks like it will just get you to about stock (67-25=42). The calculator can give you an idea of how much the tire will stick out compared to stock. Of course, tire sizes are important too.
Thank you guys. I am running stock suspension with 19 inch wheels. Can’t really tell from pictures but wheels in the picture seat a lot inside the wheel-well. I intent to use the Lobster claw wheels for track.
Sent from my iPhone using Tapatalk
Front - +10mm to +15mm
Rear- +20mm + 25mm
keep in mind I don’t know what your camber is set at or tire sizes… ride height also plays a rolls.. this should be real close to flush. Your rears with +25 spacer would be effective +21mm offset, but your .5” (or .25” per/side ) narrower rear wheels
than mine… +25 is probably a little extreme but it’ll work. Technically I’ve got more offset than if you did this
Mine is:
19x8.5 +49 with 3mm making it +46 (245)
19x10 +40 with 15mm making it +25 (285)
