Alloy wheel sizing

[Lannister902]

Hi,
I've done as much research on that subject, and I THINK I've figured it out, but want to double check before I buy a new set of alloys.

So I'm looking to change the alloy on my car. The OEM wheel size is as follows:

Front - 18x7.5j ET:45
Rear - 18x8J ET:52

I've got 12mm spacers up front and 15mm rear fitted. (changing the offset

I'm happy with that setup, and ideally want to keep it as close to that as possible with the new alloys.

The new alloys I really like are as follow...

Front: 18×8J ET38
Rear:18X9J ET42

The rears are 1" wider with the new alloys, which shouldn't be a problem. Am I correct in thinking with 5mm spacers all round, it'll match up with the look of the Oem wheels (inc the 12/15mm spacers fitted)?

[drmotorsport]

https://www.willtheyfit.com is the easiest way to check this kinda stuff.

[TA14]

Lannister902 said:

Hi,
I've done as much research on that subject, and I THINK I've figured it out, but want to double check before I buy a new set of alloys.

So I'm looking to change the alloy on my car. The OEM wheel size is as follows:

Front - 18x7.5j ET:45
Rear - 18x8J ET:52

I've got 12mm spacers up front and 15mm rear fitted. (changing the offset

I'm happy with that setup, and ideally want to keep it as close to that as possible with the new alloys.

The new alloys I really like are as follow...

Front: 18×8J ET38
Rear:18X9J ET42

The rears are 1" wider with the new alloys, which shouldn't be a problem. Am I correct in thinking with 5mm spacers all round, it'll match up with the look of the Oem wheels (inc the 12/15mm spacers fitted)?

Which car is this for? There are always odd ball bits to watch out for.

I can't really understand what you're trying to do. Are you keeping the spacers? If so the rears will be 52-42+((8-9=1)x25.4/2) = 22.7mm further out which is quite a lot for many cars (or 37.7mm further out than OEM which again is a lot.) Similarly the fronts would be 13mm further out. Then we get to tyres; original sizes and what are you proposing? 8" rim on the rear is probably a 225 or 235 as standard but your proposal will require a 255 or thereabouts so 30mm wider making the outside edge of the rear tyre 23+(30/2) 38mm further out than present or 53mm further out than OEM, quite a lot.

You usually try to size the new alloys to reduce or eliminate spacers.

[Deep Thought]

TA14 said:

Which car is this for? There are always odd ball bits to watch out for.

I can't really understand what you're trying to do. Are you keeping the spacers? If so the rears will be 52-42+((8-9=1)x25.4/2) = 22.7mm further out which is quite a lot for many cars (or 37.7mm further out than OEM which again is a lot.) Similarly the fronts would be 13mm further out. Then we get to tyres; original sizes and what are you proposing? 8" rim on the rear is probably a 225 or 235 as standard but your proposal will require a 255 or thereabouts so 30mm wider making the outside edge of the rear tyre 23+(30/2) 38mm further out than present or 53mm further out than OEM, quite a lot.

You usually try to size the new alloys to reduce or eliminate spacers.

I think hes trying to remove the spacers that he has been using, but thinks the new wheels will require 5mm spacers all round to give the same effect.

Which i think is correct, by my calcs too.

[TA14]

Deep Thought said:

I think hes trying to remove the spacers that he has been using, but thinks the new wheels will require 5mm spacers all round to give the same effect.

Which i think is correct, by my calcs too.

In that case the fronts would be 6mm further out and the rears 13mm further out before you start to consider tyres. Which may be OK depending on the car, although it's a lot of extra strain on the mechanical components, and assuming that the suspension has not been lowered also