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Worried now... Tyre sizes vs rolling radius


marzman

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Hey folks,

 

I ordered some wheels & tyres last week and im expecting delivery either tomorrow or Friday... BUT

 

Im crapping it about the rolling radius now - i dont think its right.

 

The shop advised me to get 245/40/19 on the front, and 265/35/19 on the rear, as thats the standard sizes their database recommends.

 

The difference in aspect ratio is due to the increased width... but i now think thats gonna cause me the traction control problem.

 

From the tyre size calculator, my current front to rear setup gives me:

 

225/50/17 front - 235/50/17 rear = +1.52% difference in circumference.

 

The new setup will give me:

 

245/40/19 front - 265/35/19 rear = -1.52%!!

 

So thats a 3.04% negative difference i.e. my rear wheel will now be smaller than my front. Anyone ever tried these sizes before??

 

Im a bit stuck though cos the sizes i originally wanted werent available (same with a 35 profile at the front) for another 8 weeks... so i just said yes to what they were offering. Am i screwed?

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ideal front to back stagger needs to be kept between 1/2 inch and less than 1 inch to keep the VDC, traction control happy

 

the most common size for 19's is 245/35/19 25.8", 275/35/19 26.6" though it ultimately depends on your wheels, goals, etc.

 

On my own car, I run 265/30/19, 285/30/19

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Cheers Adam,

 

I've just phoned them and they spouted all this crap about forums being the worst thing ever as nobody knows what they're talking about, and that im wrong. And that infact they have 2 employees with 350z's running the exact same dimensions as what they were sending me!

 

Then they disagreed with my figures, saying i was wrong... until about 10mins into the conversation he must have realised i was right, and suddenly started back tracking what he'd been saying... and they've now managed to find me some fronts in the size i wanted in the first place! So will be running 245/35/19 and 265/35/19.

 

So he said i should be getting them Monday or Tuesday... we'll wait and see eh?

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Cheers Adam,

 

I've just phoned them and they spouted all this crap about forums being the worst thing ever as nobody knows what they're talking about, and that im wrong. And that infact they have 2 employees with 350z's running the exact same dimensions as what they were sending me!

 

Then they disagreed with my figures, saying i was wrong... until about 10mins into the conversation he must have realised i was right, and suddenly started back tracking what he'd been saying... and they've now managed to find me some fronts in the size i wanted in the first place! So will be running 245/35/19 and 265/35/19.

 

So he said i should be getting them Monday or Tuesday... we'll wait and see eh?

 

 

rear size should be 275/35, 265 is too small.

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Yup 265 is still too small on the back. Remember Standard is 225/45/18 & 245/35/18 For 19" wheels you want

 

Front - 245/35/19 (0.8% bigger from factory)

Back - 275/35/19 (0.4% bigger from factor)

Total 0.4% difference Front-Back

 

Your proposed setup

 

Front - 245/35/19 (0.8% bigger from factory)

Rear - 265/35/19 (1.4% smaller from factor)

Total 2.2% difference Front-Back

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Cheers Adam,

 

I've just phoned them and they spouted all this crap about forums being the worst thing ever as nobody knows what they're talking about, and that im wrong. And that infact they have 2 employees with 350z's running the exact same dimensions as what they were sending me!

 

Then they disagreed with my figures, saying i was wrong... until about 10mins into the conversation he must have realised i was right, and suddenly started back tracking what he'd been saying... and they've now managed to find me some fronts in the size i wanted in the first place! So will be running 245/35/19 and 265/35/19.

 

So he said i should be getting them Monday or Tuesday... we'll wait and see eh?

 

many times they are right....but I'm not just some random forum poster :)

 

245/35 front, 265/35 rear will work just fine.

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Yup 265 is still too small on the back. Remember Standard is 225/45/18 & 245/35/18 For 19" wheels you want

 

Front - 245/35/19 (0.8% bigger from factory)

Back - 275/35/19 (0.4% bigger from factor)

Total 0.4% difference Front-Back

 

Your proposed setup

 

Front - 245/35/19 (0.8% bigger from factory)

Rear - 265/35/19 (1.4% smaller from factor)

Total 2.2% difference Front-Back

 

245/35 front, 265/35 rear will work just fine - total stagger is 2.1% front to back .6% difference from factory), which is more than acceptable

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