Wider tires on stock 20" rim

[1russianguy]

On the AWD Performance model with performance option, assuming all the stock wheels (20x8.5?) are the same, would like to put on wider all-season performance tires. Idea is to use the same tires when I upgrade to after-market rims. Has anyone installed a slightly wider tire on the stock 20" rims? (assuming it's fine going from a 235/40 to a 245/40) Thanks in advance!

 

[1russianguy]

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[Snow Drift]

It depends on the size of the tire. Check out tirerack.com for the manufacturers recommended size limits.

My STI comes with 19x8.5 and stock tires are 245/35. You could get away with 255, but the % beyond stock is a bit much for most sizes, so not recommended.

 

[Zaphod]

On the AWD Performance model with performance option, assuming all the stock wheels (20x8.5?) are the same, would like to put on wider all-season performance tires. Idea is to use the same tires when I upgrade to after-market rims. Has anyone installed a slightly wider tire on the stock 20" rims? (assuming it's fine going from a 235/40 to a 245/40) Thanks in advance!

A wider tire of the same sidewall profile will have a slightly larger diameter. Larger diameter has larger circumference which will cause the speedometer reading to be slightly off, reading slower than you are actually traveling at. Going from 234/40 to 245/40 wouldn't be a huge difference, it will nonetheless impact the reading slightly.

 

[lairdb]

Considerable discussion of this over at M3OC; see particularly this post: Performance and dual motor are happening (per Elon)!.

More generally, read posts by @Mad Hungarian, including:

Wheel and Tire Tech
Wheel/Tyre Discussion
Performance and dual motor are happening (per Elon)!

 

[Mad Hungarian]

On the AWD Performance model with performance option, assuming all the stock wheels (20x8.5?) are the same, would like to put on wider all-season performance tires. Idea is to use the same tires when I upgrade to after-market rims. Has anyone installed a slightly wider tire on the stock 20" rims? (assuming it's fine going from a 235/40 to a 245/40) Thanks in advance!

245/45R20 will work fine on the OE wheels and is only 1.1% larger in overall diameter, so at 60 mph your speedo will only be off by about 0.6 mph. Note that the difference in O.D. from when your tire is new compared to when it is worn to the wear bars is on average about 2.0%, so this isn't a big deal. As an alternative you can also run a 255/30R20 on the OE wheel, which has a 2.0% smaller O.D. But that as big as you can go on the 20x8.5.

 

[lairdb]

245/45R20 will work fine on the OE wheels and is only 1.1% larger in overall diameter, so at 60 mph your speedo will only be off by about 0.6 mph. Note that the difference in O.D. from when your tire is new compared to when it is worn to the wear bars is on average about 2.0%, so this isn't a big deal. As an alternative you can also run a 255/30R20 on the OE wheel, which has a 2.0% smaller O.D. But that as big as you can go on the 20x8.5.

Do you mean 245/35? 245/45 is almost 10% larger, two inches taller...

 

[ybbor]

I wonder if a slightly wider tier would help with how easy it is to curb the stock rims and stock tires.

 

[Mad Hungarian]

Do you mean 245/35? 245/45 is almost 10% larger, two inches taller...

My bad, sorry about that... yes, 245/35R20.

 

[240W]

Personally, the 235 looks stretched and 245 looks like it’s square, fits better on the 8.5...

Also, on another thread, it’s mentioned that the speedo is gps corrected so it should be self correcting. Wonder if anyone here test that via some type of logger?

 

[Gouldness]

Personally I like 1010tires.com they have a good fit calculator and show the % that you want to be within (I've heard 3 or less). I'm going with 245/35/20's all around (square) on custom 20x8.5's with a 1 inch drop from Tsportline's new awd springs.

 

[lairdb]

If I don't trade someone for 19s, I'm thinking 245/35R20 square.

Looking at TireRack, there's a Pilot Super Sport in that size available (at least for now, though I think that line is on its way out) with acoustic foam, but there's no Pilot Sport 4S with foam; that's only in the original 235/35R20.

(Of course, there's also Hoosiers, and Pirelli Corsa and Trofeo, and. other ways to burn up money and die in the rain...)

 

[aspec818]

Anyone with the oem 20's upgraded to the 245/35/20 at this point? Any differences visually or the ride?

 

[bradhs]

Anyone with the oem 20's upgraded to the 245/35/20 at this point? Any differences visually or the ride?

I did, see this thread: 245/35/20 on oem 20” wheels?