8 replies to this topic

[Liam S]

Hi all,

This has been an ongoing question in this forum for sure, but trying to narrow down a single definitive answer for this is difficult for LX Sedan.

17 x 10 rears with 275/40’s;
- Diff 1400mm face to face with shock mount moved inboard approx 25-40mm, commodore disc brakes
- Mini-tub and minor chassis lip massaging
- A9X style flares (140mm wider version)
I’m thinking 5” backspace?

17x8 Fronts with 235/40’s;
- HX Stubs with UC UCAs
- Cutting recess at firewall joint for full lock travel clearance
I’m thinking 4.5” backspace?

Any advice, tips or input that I’m on the right track? Cheers lads.


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[76lxhatch]

... trying to narrow down a single definitive answer for this is difficult

 

There is no definitive answer. Tyres, the exact offset and width of different wheels, brake setups, flares all differ. Even the wheel alignment affects clearance, and the tighter the clearance the more accurate you have to be. The only safe answer is to measure what will fit on your car, this doesn't have to be expensive:


Having said that your numbers look like they could work. No doubt you're looking at spending a lot of money on wheels and tyres and you want to be sure, but I'm not going to stick my neck out and make any guarantees.

[Liam S]

There is no definitive answer. Tyres, the exact offset and width of different wheels, brake setups, flares all differ. Even the wheel alignment affects clearance, and the tighter the clearance the more accurate you have to be. The only safe answer is to measure what will fit on your car, this doesn't have to be expensive:


Having said that your numbers look like they could work. No doubt you're looking at spending a lot of money on wheels and tyres and you want to be sure, but I'm not going to stick my neck out and make any guarantees.

Yep, I’d assumed there would be more to it, otherwise there would be a sticky about it .

Appreciate the input regardless. I’ve heard the 5” backspace on rears is a pretty commonly done thing, it’s more the front backspacing that has me stumped tbh. Problem being, (if you can call it a problem) I will need to rip the front end out to mock fit all that components first to make sure they will fit.

The rear is a bit trickier.


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[rexy]

With a 17” on the front you can go a bit further in as you clear the upper ball joint which !5” usually dont. I ran 5.5” on mine but tyre size will contribute to which bits of the bodywork you run into clearance problems with.

[Liam S]

With a 17” on the front you can go a bit further in as you clear the upper ball joint which !5” usually dont. I ran 5.5” on mine but tyre size will contribute to which bits of the bodywork you run into clearance problems with.

So a 4.5” backspace will work OK for the most part?


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[gtrboyy]

Cant really remember where seen diagram & advice etc but was probably Custom Steel Wheels old website or fb something about rims being 1" wider at ridge than what you order also not accounting for sidewall width catching people out.

 

Kind of like ordering diff giving BUF measurements then diff is still wrong length when they don't account for difference between disc or drum brakes etc

 

Make sure you measure it all up properly with drawn diagrams & triple check before ordering

[Proto]

you may find these links useful

 

https://www.willtheyfit.com/

https://tiresize.com...ize-calculator/

[gtrboyy]

bciwheels website

 

[Uncle Chop Chop]

I used to run a 5.1" backspace on the front and it just cleared with a 15" steel rim. Please keep in mind that I used a VB - VP front disc, so the bolt up face on the disc may not be in the exact same spot as the LH - UC disc. Also bear in mind that whilst the wheel fit, the knock on wheel weights used to clip the top ball joint. The noise went away after about 15 minutes though.