Need an answer for understanding the numbers!

[kh92]

For example..

Profile: 235/40/18
Wheels: 18x8.5 +45 Offset

I have no idea what the numbers are for! I don't know what an offset is! And what matches what?! Someone explain to me please! Thanks in advance.

---------- Post added at 11:46 PM ---------- Previous post was at 11:43 PM ----------

Oh, and the only things I know are the 18 is the 18 inch rims.. and 235 is the width thickness of the tyres.

[MattMPS3]

The tyre numbers break down like this
235 - 235mm width
40 - 40% of 235 = 94mm, this is the tyres profile, or sidewall height
18 - 18" wheel diameter

Another thing that MUST be checked is that any replacement tyres satisfy the cars load rating, it is on the tyre placard, I cant remeber the MPS's spec off hand, but there will be a number like 89
You also have the minimum speed rating on the placard, while you may have no intentions of exceeding 240 kph, you still need to satisfy the minimum rated requirements, although most decent tyres in these sizes usually carry a W rating (300+)

Failure to follow these minimum requirements can, and has caused insurance companies to deny claims.

Wheels
18 - 18" diameter
8.5 - 8.5" wide
Offset +45, this is how far off centre the hub sits, so a +45 off set means the wheel hub is at 45mm closer (from the centerline) to the outer edge of the rim, a higher offset +52 sits the rim deeper in the guard, a lower offset +38 sits the rim further out, i.e hella flush.

Here is a great calculator you can use to compare different wheel & tyre combinations, and see how they compare against your stock setup.

Custom rims, wheel tire packages for your ride - RIMSnTIRES.com

From memory the stock MPS wheels are 18 x 7 +52.5, stock tyres are 215/45/18

[Damnfuzz]

Oh dude, prepare to get flamed for not using search functions prior to posting this little clanger.....
I managed to google this out of laziness in less than a minute...

Start here:

Offset - 1010tires.com Tire & Wheel Tech
Reading your tyre - Reading your tyre size

Basically, the cut and thrust of the size you posted above is:

235 - the width of the tyre in millimetres
40 - The aspect ratio of the tyre, ie the sidewall height as a percentage of the tyre width
18 - The diameter of the wheel
18x8.5 - The wheel dimensions, 18 being the diameter and 8.5 being the width, in inches (we love to mix metric and imperial measurements)
+45 - the offset of the wheel, ie the distance of the mounting surface of the rim to the wheel's true centreline

As for what matches what? For example the Gen I 3MPS is 215/45 R18x7 +52.5. Jump on somewhere like 1010tires.com and do some searching with the tyre size and wheel offset calculators to get an idea about what will work. Or research it first on here...

Search.....search.....search.....search.....

Adrian

[SarcasticOne]

Oh dude, prepare to get flamed for not using search functions prior to posting this little clanger.....
I managed to google this out of laziness in less than a minute...

Haha, ironically, don't think he would get flamed on these forums, maybe a link to a post describing it, a link to a website describing it, or if I was first, it would be a lmgtfy link

Also, Pretty sure stock gen 1 tyres are 89W

[Caffeine Fiend]

Yeah, flaming's not something I've seen a lot of here. Unlike the Mazdaspeed forums in the US

As has been pointed out though, you'll get more people willing to assist if you show you've tried to find the answers yourself, as opposed to asking things that have been covered and documented a few times on the forums here

Like the lord, OzMPS helps those who help themselves

Nobody wants to crush your enthusiasm though. It's great that you're exited about your car as that's what they're all about . Just make the search engine here on the site your friend and you shall be richly rewarded with the informational juices that flow freely from this forum

[MattMPS3]

Like the lord, OzMPS helps those who help themselves

Note to self, change forum moderator title to forum apostle, I even have the right name

[Caffeine Fiend]

Note to self, change forum moderator title to forum apostle, I even have the right name

Is that just a thinly veiled excuse to get away with wearing a toga Matt?

Be honest now


Sent from my iPhone using soon to be uninstalled POS Tapatalk App (fix the damn app you mofos!!!)

[MattMPS3]

Its a perfectly good excuse for wearing a thinly veiled toga.

[Caffeine Fiend]

*is thankful the forum isn't webcam enabled*




Sent from my iPhone using soon to be uninstalled POS Tapatalk App (fix the damn app you mofos!!!)

[Damnfuzz]

Sorry guys, perhaps I came across a bit harsh. It was very early in the morning and I hadn't had breakfast.... Note to self: eat breakfast, THEN read OzMPS...

I suppose I just meant have a good hunt around on the forum for info such as this, and failing that, use a search engine such as google to find stuff. I knew the answers but went searching to help ME understand how easy it was to find. Turns out I found the info really really easily with a minimum of searching.

And Matt, no more thin toga talk. People are already becoming concerned...