itsfast

Can anyone help me with tire sizes for 20x8.50 front and 20x9.50 rear wheels? I spoke with a rep. at tirerack and he told me i needed 245/30/20 in the front and 265/30/20 in the rear for proper height and fitment. He said in no way would a 275 or 285 fit in the rear on a 9.5 inch rim. Ive always trusted tirerack through the years but this doesnt sound right. Also the front rims are offset at 35mm and was told i may need spacers to clear the brakes. any thoughts? thanks so much for the help/opinions

*the vehicle suspension is stock*

AKnight55

245/30/20 Front and 275/25/20 or 285/25/20 Rear

Viet_Amg408

put 275 or 285 on a x9.5 wide will make you look like you on crack..



245/30/20 in the front and 265/30/20 is correct..

desired_speeds

275 will be fine.

randallaguirre

I have 285/30-19s on a 9.5 rear rim. They tuck no problem and I like the way the tire is slightly wider than the rim---just in case I tap a curb.

JayhawkPharmD

I have 275/30/20 on the rear. No problems. Good luck.

HeissRod

:r olf:

You don't know how wrong you are.....

AKnight55

Yea not sure about that... I run a 275 on a 9.5 inch wheel.. You need all the traction you can get with these cars and a 265 is certainly not doing you any good.. Clearly your going for the stretch tire look, the majority of people aren't going for that look.

komp55

When you're buying tires for a specific size rim as a "plus size" fitment, there are two primary considerations. The first is to make sure that the overall tire diameter is as close as possible to the OE size tire. This is necessary because it affects the overall gearing of the car, as well as the accuracy of the car's speedometer. The second consideration is whether the tire size in question is an approved size for the wheel you plan to mount it on. This second consideration is more important from a safety standpoint than the first issue, particularly with very low profile tires, because the design integrity of the sidewall can be compromised if it's pinched in by mounting it on a wheel too narrow for it, or by stretching it out to mount on a wheel that's too wide for it. This is why every single tire manufacturer specifies the approved rim width range for a particular tire size they manufacture; if you mount the tire on a wheel the tire wasn't designed for, it's on you - not them; your life, not theirs.

Let's look at the above information in the context of a W211 E55, which came from the factory fitted with 245/40/18 front and 265/35/18 rear tires mounted on 8" and 9" wide wheels, front and rear respectively. The stock overall tire diameters are 25.72" front and 25.3" rear. This means your plus size fitment ought to be as close as possible to these respective diameters in order to retain the correct gearing of the car and its speedometer accuracy.

Tire Rack's recommendation for the front size is correct. A 245/30/20 has an overall diameter of 25.79", which is almost identical to the stock size of 25.72". You're concerned about Tire Rack's recommendation of a 265/30/20 for the rear. Given the wheel width you've indicated of only 9.5", that's also an appropriate recommedation since the approved rim range for that size tire is 9" - 10". The next size wider tire, a 275/30/20, also requires a 9" - 10" rim, but its overall diameter is way too tall, coming in at 26.5" - which is over a full inch taller that the stock tire diameter and is not recommended. The tire size that does work is the 285/25/20, with its diameter of 25.61". Unfortunately for you, this size tire requires wheels with a 10" - 11" width for safe mounting, with most tire manufacturers specifying use of a 10.5" wide wheel only. It's just dumb to mount this size tire on a rim it wasn't designed for.

A third factor to also take a look at is the load range of the tires in question. In the case of 20" wheels on an E55, there's little doubt that the correct size front tire, a 245/30/20, is way down at the lower end of a safe load index for a heavy car like the W211 chassis, while the correct sized tire for the rear, a 285/25/20 has a completely sufficient load range. If load range issues concern you, then consider using a 255/30/20 in front, but know that it will be about a quarter of an inch taller than the stock tire diameter, which isn't much different than the 285/25/20's diameter is over its equivalent stock diameter of 25.3."

HeissRod

275/25_20
25.4" diameter

done

komp55

Bad choice. Here's specs for that size tire:

Specifications for tire
size: 275/25 20

UTQG: 220 AA A
Load Index: 91
Max Inflation Pressure: 50 psi
Tread Depth: 10/32nd"
Rim Width Range: 10.5-11.5
Meas. Rim Width: 10.5
Section Width: 10.5"
Tread Width: 11.9"
Overall Height: 25.8"
Revolutions per Mile: 805

Not designed for a 9.5" rim. Plus, load index on a 275/25/20 is only 91. Load index on the stock 265/35/18 is 97. Huge difference in safety margin. I wouldn't run this size on a 9.5" wide rim under any circumstances.

HeissRod

All that is a moot point at TireRack doesn't carry a 275/25_20

P.S. Where did you get your specs? You have the diameter listed as 25.8"? You sure you aren't looking at specs for a 295/25_20?

AKnight55

Im not sure what your talking about... A 275 tire fits perfectly on a 9.5 inch wheel... This is my exact set up..A 285 tire will even work on a 9.5 inch wheel..

To the OP, go with a 285/25/20 as so many have already done..

Komp55... I just looked at one of your old posts and it says your running a 275 on a 9.5 wheel, so where do you come off saying it wont work??

komp55

On a 19" rim. With a 30 aspect ratio. Big difference.

AKnight55

so your saying on a 20" rim a 275/25/20 or 285/25/20 wouldn't work on a 9.5 inch wheel?? That doesn't make sense..

Staff@RPM

Well, just to state what I am using on a 20"x9.5" wheel is a 295/25-20 Conti. I think it's crazy to stretch a 265 onto a 9.5" wheel.

I'm not a big fan of the stretched look so I went with a wider tire, just my taste.

komp55

Let me explain it again. There is a significant difference between what size tire you can physically mount on a particular rim and what size rim width is specified for a particular size tire. I'm saying a 285/25/20 tire should NOT be mounted on a 9.5" rim because the rim is narrower than what the tire was designed for. Most tire manufacturers specify a 10.5" wide rim for this size. Same issue for a 275/25/20 tire. The minimum specified rim width is 10" (see Nitto Invo specifications for this size tire at Nitto's website). Plus, this size doesn't have a sufficient load index for a heavy car like the W211, so it's an unsafe choice from that perspective as well.

Can both size tires be mounted on a 9.5" wide 20" diameter wheel? Of course, but that's why we have stuff like the annual Darwin awards. YMMV.

AKnight55

OEM is a 265 on a 9" wheel, so I would needing a 10" wheel for a 275 is a bit conservative. Personally I'd go with a 285/25/20 and roll the fenders a bit to avoid any rubbing...

GregMB

Is there any wheel offset that will allow for the use of a 285-width tire without resorting to rolling the rear fenders? Tucking the wheel in a little deeper into the wheel well may just move the problem from the fender lip to rubbing against the suspension bits....


-G

HeissRod

Lots of cars here run 285s. I'm running 285s on a 10.5" wheel and I'm lowered with STAR.

dychen

Aren't the P30 package wheels 9.5" wide running a 265 tire in the rear?

skratch77

I thought e55s had 9.5 in the rears?

When I ordered my wheels they kept pushing me to get a 10 in wide wheel but I told them I wanted to run a 265 or a 275 max on them.

I ended up going 18x9.5 in the rears with a 275/35/18

AKnight55

Stock e55 wheels are 9" rears, im almost positive..