mondo

Guys, are any of you that are running 20's having trouble with unusual tyre degradation? I recently had a set of fronts and later, a set of rears fail due to wear on the inside edges. The fronts i suspect was due to an alignment issue with excessive toe in, but the rears failed less than 3000km after a wheel alignment. I took the car back to be checked and the alignment guy is happy there is nothing wrong with the rear setup, but did find that the front right was again scrubbing the inside edge. he found that tyre had only about 22 pounds in it (i had not checked for a couple of weeks) so was not sure if it was that or the alignment. i asked him to do another alignment on the front anyway. To the eye, that tyre did not look under inflated but it is really hard to tell with the narrow sidewalls. This is the first car i have run with bigger than 18" wheels so the narrow sidewalls are new to me.

so i am wondering if maybe i am having issues due to the way the cars sit when on 20's or if i am running too low a pressure in my tyres? I have been running 36 pound.

'03 W211 E55. tyres are 275/30R20 rears and 245/30R20 fronts and compounds are equivalent to your summer tyres. any help appreciated?

This was one of the rears

w204_racing

mondo

Nah, there's no rubbing

mondo

just giving this a bump ^

w204_racing

Strigoi

Something was rubbing on the tire. That was not an alignment or tire pressure issue.

What ET are the wheels that you're running?

mondo

because there are no witness marks anywhere in the wheel arch or on the components within the wheel arch. if it was rubbing, there will be evidence of it. I also had the car inspected on Friday by a specialist who is happy there are no issues with the rear setup.

offset is +42 wheel is 20x10J

the guy who stripped and fitted my new tyres said he feels that they were just rubbish tyres and if they were a little under inflated, that could be the cause. he's right abut the quality of the tyres, they were rubbish. not sure about the other point though, hence my question if others had had a similar issue.

StarvingArtist

I had a tire do that. Wore it right down to the air! The wear point is just around the corner from the tread, so you really have to get down and look. I spent many thousands fighting this battle. Five sets of 19's aren't cheep. The lower the profile, the less toe in you can run because there's less sidewall flex. The negative camber concentrates all the wear on the inside edges. FRONT... I replace all the ball joints every 40-50k. I run K=mac bushings in the thrust arms,and I slotted the holes in the sub-frame where the control arms bolt on to adjust out the rest of the negative camber. I built a wooden jig to set the toe. I run .020" difference between the front edge of the rim and the back edge total. .010" each side. No idea what that is in degrees, but it's the sweet spot for 255-35-19. The toe changes dramatically with height, so the car has to be well settled to be accurate. I back it out of the garage and roll it back in every time it gets jacked up. REAR... There is a ton of flex in the rear, and it toes out under power, so you need some toe-in or it gets weird when you go to pass someone. I'm running K-mac bushings maxed out in the rear for camber, but I wasn't real happy with how it came together, and adjusting the toe was a pain. To be fair though, I've had no problems for 4 years and 50+k miles. If they ever fail I will figure out what to do next. I run about .025" total toe in the rear. 285-30-19 That's not enough, but I've gotten used to it, and the only wear on the back tires is from the gas pedal. I've got 30k on my current tires, and two just got taken out by a pot hole.
Going with 295's in the rear this time. If the computers don't freak out, I'll go for 305's next time.

mondo

cheers for that info. much appreciated. in 11 months i have replaced the rears twice and the fronts once. the first set of rears was tyre age because the car had sat mostly in a garage for 7 years undriven. as you said, it is an expensive exercise... i'm in the process of trying to find someone willing to swap my 20's for a set of 19's or even 18's. i would like to take it on the track for some circuit days occasionally, but not while it sits on 20's.

hachiroku

i believe we're supposed to run something like 42 or 45 psi in the tires...from the looks of it you were running LOW on air...for a very very long time. at anytime you are running lower profile tires, you must check your air pressure regularly. low profile ties tend to not show when they're low on air very easily. I know because on my Audi I drove for 2-4 weeks with what i thought was a little lower (thought i was at 25psi) air pressure but in actuality was more like 8-15psi...my tire wore just as yours did and i also damaged my wheels hitting a metal plate.

I run 20 inch wheels and tires.

when vehicles lower or squat, generally you receive negative camber and possibly toe changes. at my last alignment, i contemplated getting my car aligned at sport 2 setting as its lower, but stuck with alignment at comfort. I also have more wear in the inner tread versus the outer, but for a good while i was running 2 inches lower all around using my electronic lowering module. have been running the same tires on my car for easily over 10k miles with a good amount of tread left.

this is the only treadwear guide i could find online and i'd say should be half of the listed miles rating. my Hankook V12's are rated at 320 and should make it to 20k miles...my rears on the other hand...no way. i lay on the throttle wayyyyy to often, but am very happy they've lasted so long.

StarvingArtist

Looking at the picture again, it does look like the sidewall came apart rather than wore through.

hachiroku

sidewalls when not supported by enough air are being pushed and pulled in opposing directions. this causes the belts (steel or fiberglass) to separate from each other as well as from the rubber. once this occurs a bubble will form. once a bubble forms its only a matter of time before the thin membrane bursts causing the entire sidewall to separate from the bead. certain tires do better, certain tires do worse. i personally prefer Hankook V12's over my Sumitomo HTR-Z II due to the usage of steel reinforced sidewalls. reinforced sidewalls take A LOT more abuse from stretching over wide wheels as well as abuse from running low in air.

the tires in question use a fiberglass reinforced sidewall...very very susceptible to blow out when low on air. steel reinforced sidewalls will put up more of a fight before blowing, but all in all can and will still blow given the right circumstances.

maybe not steel sidewalls but definately "reinforced"

mondo

yes the tyre failed due to running deflated, but, the wear i was getting caused air to escape the tyre. sort of a what came first, chicken or the egg situation.

very much appreciate your input and yes, i will definitely be heading to the garage to check tyre pressures before i drive anywhere in future. while 20" wheels look sexy, the small sidewalls are a pain in the ****.

Yuille36

I was just about to say that, that tire looks like it was under inflated. Checking air pressures is critical, if your car isn't equipped with TPMS.
And that reminds me, that I need to check mine again.

mondo

a friend recently bought a TPMS system the connects via bluetooth to your phone. i think i will invest in those.

Yuille36

Or the alternative is to run nitrogen in all your tires, nitrogen molecules are larger than air, so it's harder for any nitrogen to leak thru the tire. And the nitrogen will stay at a constant pressure longer then air. And it pretty cheap insurance.

mondo

have run nitrogen on other vehicles. not sure if anyone where i live now offers it? there's only 1 tyre shop within 30min drive of here.

Yuille36

I can just imagine what it would be like to have a catastrophic blowout at 120 kph or 80 mph. It's a wonder that the tire held together, had it come apart.

mondo

I was doing about 70mph on a highway when it let go. just felt like a bad vibration tbh. my first thought was that the transmission had failed, then realised what it was and pulled over immediately. Had done a 400 mile road trip that day and was luckily only about 8 miles from home.

Yuille36

Yes, you were lucky, as it could have been much much worse. You could have lost control and wrecked, and injured yourself and others.

MACEDON

45psi????? Even for stock wheels and tiresize?

hachiroku

have you never looked at the label at your drivers side door sill? its like 42-45psi...i actually run 48psi on my car. also our cars require XL tires... "extended/extra load"...these tires have thicker sidewalls and generally require more pressure for the heavy car they are spec'd for.

CharlyE500

I put only 36 psi for all tires... is this mean too low ?

hachiroku

yes you are too low...confirm with the tire inflation guide located in your car. my car with stock wheels never felt great when the tire pressure was lower than recommended. traction was worse in turns.

lseguy

i just checked the drivers side doorjamb label on my 2006 e55. 32psi for front/36psi for rears for the stock 18" wheel setup is what the label says. I have 19's and have been running 36psi all around for a couple years now. My offsets are 32 front and 40 rear. Just put on all new Pilot Sports as my fronts did wear on the inside edges. My rears wore evenly/perfectly fine. Im running 265 35 upfront and I think 285 30 on the back. (forgot to double check when I went outside to see the label in the doorjamb.). I just recently installed all 4 new front lower control arms and new airstruts upfront and a fresh 4 wheel alignment. Ill monitor my tires closely to see how the wear goes