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Tire cupping with Sumitomos

Discussion in 'Gen 2 Prius Main Forum' started by jlp357, Aug 19, 2008.

  1. jlp357

    jlp357 Junior Member

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    Had to make a rush purchase of new tires in early January. Could not get Michelin Hydroedges without special order and time did not permit that. Purchased Sumitomo Touring LSH recommended by manager at Tire Kingdom in a larger size than the OEMs. The complete description was 195/60R15 88H, STH41 70,000 mile tires filled with nitrogen to 35/33 psi. The first thing we noticed was a drop in mpg to 43 and it never got better. In Florida we had some nitrogen added to the tires 38/36. Mileage did not increase more than 1-2 mpg at the most. Upon return to local tire dealer from whom we purchased the tires we had nitrogen added to 40/38 psi. After 10,000 we noticed a noise and it got louder and more annoying. Tires have been rotated every 6,000 miles. Today with about 15,000 miles on this set we learned that all of our tires are cupped on the inside edge which accounts for the endless noise.

    The dealer told us that the tires were too wide and that is what caused the cupping. That is interesting since so many on this board have put the larger tires on their cars with no problems.

    Dealer checked the alignment and told us it was only slightly out but he recommended we have it aligned before we put other tires on it. We agreed. Only after we paid for the alignment did we get a copy of the alignment specs and we headed home. At home we studied the report and learned that our alignment was within all tolerances before they did anything to it. They chose to make some minor adjustments but that was to get our money!

    They are offering us credit on the unused tread toward the Michelins we wanted in the first place. Our thought is to put on the OEM size but we are questioning now whether we want to go with Hydroedge or Primacy. We do NOT want any more Sumitomos!!! Will the Primacy give a softer ride than the Hydroedge? We are concerned with LRR and according to a post on this board the HE have a slightly better LRR than the Primacy. We just don't want to take a hit on mileage which averaged 48 with the OEM tires but dropped overall to 44-45 with the larger Sumitomos. Any suggestions from those who have walked this road before and now have experienced15,000 to 20,000 miles on either of these tires? Also, any suggestions as to why all 4 tires cupped on the inside??
     
    #1 jlp357, Aug 19, 2008
  2. V8Cobrakid

    V8Cobrakid Green Handyman

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    i get really bad cupping too...
     
    #2 V8Cobrakid, Aug 19, 2008
  3. thepolarcrew

    thepolarcrew Senior Member

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    Looked at how the car and how it sat on level pavement the other day. Looks like they have a lot of camber to begin with. Adding air is suppose to make the tire ride higher in the center. Has me wondering though.
     
    #3 thepolarcrew, Aug 19, 2008
  4. bwilson4web

    bwilson4web BMW i3 and Model 3

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    I've just started on my second set of Sumitomos and the first had some scalloping on one tire from the wheel with the worst caster. The first set had just reached the 'wear bar' so it was time and I did get almost all of my miles out of them. A screw picked up on the outer edge of one other tire led to a slightly earlier replacement than planned but I'm satisfied with the 50k miles and have a nice, full-size spare. Also, I wanted to try a different size:

    • 175/65R14 - original
    • 175/70R14 - next set
    Since I just put new Sumitomos on, I've adjusted the front camber to nearly 0' and a very small, positive toe. I'm working on the rear wheel alignment and should have them to -0.8 camber and 0' toe by the end of the week.

    I'm using Sumitomo T4s, listed by Consumer Reports as a low rolling resistance tire. This series is rated up to 50 psi and that is where I run them. We have good pavement in Huntsville AL.

    The larger diameter tires cause my miles to read 5% lower, speed 5% lower, and miles per gallon 5% lower. So to cruise at 65 mph, I need to be at an indicated 62 mph. However, cruising at indicated 65 mph tends to keep me in the normal USA traffic 'pack' and the vehicle control laws remain quite happy.

    So far, I have no complaints and won't really look at any mileage changes until I get the rear toe and camber as close to my specifications as I can get them.

    One other observation, I drove 750 miles to HybridFest with the larger tires on the front and the smaller diameter tires on the rear. I noticed that a lot of the 'neutral wander' become 'neutral neutral' with the larger tires. I suspect a slightly larger angular momentum made them work like gyroscopes and track better. When I drove back with the smaller ones on the front, the car reverted to "neutral wander" mode.

    Bob Wilson
     
    #4 bwilson4web, Aug 19, 2008
  5. Casey123

    Casey123 New Member

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    I have to say I had the Sumitomos on my Honda Accord and I hated those tires. Quiet yes, good grip on dry road but once it got wet look out they hydroplaned. I did a search on the web and found out other owners experienced the same thing. Exchanged them within a week for the Michelin harmony and never looked back. The harmony is one nice tire, quiet and handles well in wet and dry conditions.
     
    #5 Casey123, Aug 25, 2008
  6. cairo94507

    cairo94507 Active Member

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    cupping is not tire related, it is alignment and shock related.
     
    #6 cairo94507, Aug 26, 2008
  7. amm0bob

    amm0bob Permanently Junior...

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    It could also be balance... but it is usually shocks.
     
    #7 amm0bob, Aug 26, 2008
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