18" tire sizing, what aspect ratio?

[damnsupra]

Hey guys,

I'm ordering rs4 ventus tires for my 18" te37

What aspect ratio should I be going, most people are saying 40 all around

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[mrtg_98]

Hey Evan

I'm running the factory Michelin Pilot Super Sport tires on my 18" TE37's. They are 255/40 at the front and 275/40 at the back.

Cheers from Switzerland

 

[Dannyvandelft]

Hey guys,

I'm ordering rs4 ventus tires for my 18" te37

What aspect ratio should I be going, most people are saying 40 all around

Depends on how wide you go. A 40 sidewall on a 255 is shorter than a 40 on a 305.

 

[damnsupra]

i basically want to go 265/40/18 and for rears 295/40/18

 

[PearlSup]

i basically want to go 265/40/18 and for rears 295/40/18

After my current set, I’m going up to 265/40/18 on 18x10 [F] & 285/40/18 on 18x11 [R].

If you go 295 in the rear, I believe you’ll need to get an aspect ratio of 35.

 

[kappa_md]

After my current set, I’m going up to 265/40/18 on 18x10 [F] & 285/40/18 on 18x11 [R].

If you go 295 in the rear, I believe you’ll need to get an aspect ratio of 35.

Doing this exact same setup. 265/40/18 on 18x9 front and 285/40/18 on 18x10 rear. Lowered on Eibach ProKit. Should be fine on street setup right? I’m thinking if I’ll be going 35 series on 18s and lowered, I’d be scraping alot more

 

[digicidal]

Doing this exact same setup. 265/40/18 on 18x9 front and 285/40/18 on 18x10 rear. Lowered on Eibach ProKit. Should be fine on street setup right? I’m thinking if I’ll be going 35 series on 18s and lowered, I’d be scraping alot more

Might scrape a bit more, but it would only contribute ~0.4 inch in rolling height reduction. Don't have the Eibach kit myself so I can't say for sure, but I'm guessing the total would be about a 1.25" drop from stock? Definitely wouldn't be taking speed bumps head-on, but shouldn't be a problem on most streets.

In your case though, stepping up to a 275/35 and 295/35 starts to be a problem with the wheel widths - as that's at the very limits of what fits on 9"/10" wheels - unless the "muffin top sidewall" is something you're looking for.

 

[TYMBOM]

Hey guys,

I'm ordering rs4 ventus tires for my 18" te37

What aspect ratio should I be going, most people are saying 40 all around

Literally put mine on today

 

[PearlSup]

Doing this exact same setup. 265/40/18 on 18x9 front and 285/40/18 on 18x10 rear. Lowered on Eibach ProKit. Should be fine on street setup right? I’m thinking if I’ll be going 35 series on 18s and lowered, I’d be scraping alot more

The reason I went 40 aspect ratio front and 35 aspect ratio rear is to minimize size differences between front and rear.

Here is the comparison of both setups using a tire size calculator:

Currently lowered on H&R springs with a TRD style front lip and have not scraped once.

 

[FLtrackdays]

I thought this page was mega helpful:

GR Supra Wheel & Tire Fitment Guide – APEX Race Parts

and actually this:

Running 18” Wheels on GR Supra? Choose Your Tires Wisely. – APEX Race Parts Blog

 

[kappa_md]

I thought this page was mega helpful:

GR Supra Wheel & Tire Fitment Guide – APEX Race Parts

and actually this:

Running 18” Wheels on GR Supra? Choose Your Tires Wisely. – APEX Race Parts Blog

Yes this has been really helpful! Thank you! The APEX team recommends a 35 series for the 18s (oem+ staggered) but I need to put in the “lowered on Eibach ProKit” equation so I thought I need to be near the stock 19s diameter size thus shifted to 40 series from 35 series. I like the look of the 18s more with meatier tires and the stock BBK fills the 18s pretty well compared to 19s. A bit wider width than stock, more wheel protection from curbs and side street elevations and lighter unsprung weight are my goals for the 18s.

 

[kappa_md]

Might scrape a bit more, but it would only contribute ~0.4 inch in rolling height reduction. Don't have the Eibach kit myself so I can't say for sure, but I'm guessing the total would be about a 1.25" drop from stock? Definitely wouldn't be taking speed bumps head-on, but shouldn't be a problem on most streets.

In your case though, stepping up to a 275/35 and 295/35 starts to be a problem with the wheel widths - as that's at the very limits of what fits on 9"/10" wheels - unless the "muffin top sidewall" is something you're looking for.

Thanks so much! I’m maxing out the tire width (265 on 18x9 & 285 on 18x10) Luckily Michelin PS4S offer the tire specs I need on 40 series also A nice drop but with a bit of ground clearance and lesser scraping

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