Putting larger tires on Viking 48

Discussion in 'eXmark' started by MacLawnCo, Dec 17, 2003.

  1. MacLawnCo

    MacLawnCo LawnSite Bronze Member
    Posts: 1,847

    I found a pair of tires i would like to put on a viking... CARLISLE TURF MASTER 18-8.50-8
    Could these tries be put on the 48" viking? I know it would alter the deck pitch, but couldnt that be compensated for by raising the wheels higher into the engine frame?

    Is there anything i should be aware of by switching these out for the stockers? Would i be able to use the stock rims? Thanks
    [​IMG]
     
  2. eXmark

    eXmark Manufacturer / Sponsor
    Posts: 4,258

    Mac,

    There are two things to be concerned about. First the tire is wider so you'll want to make sure they don't rub against the hydro lines or anything else. Second the tires are also taller.

    With the replacement tire 2" taller it should effective raise the mower 1" or at least if everything is dimensionally correct. Chances are the tires may or may not be 2" taller. They may be more or they may be less. You'll want to measure your current tire mounted and aired up and then compare that to the new tire after it's mounted and aired up. In theory you should be able to compensate by raising or lowering the rear wheel motor brackets. Each hole raises or lowers the engine deck 1/2". Other than throwi
     
  3. MacLawnCo

    MacLawnCo LawnSite Bronze Member
    Posts: 1,847

    Terry,

    i guess what i should have told you was the reason behind the larger tires. I feel that these mowers, with their smaller tires have problems with compaction...i was hoping to reduce it with new tires. At the same time, i was hoping to widen the wheel base. To do that, would i need to get offset rims, or how would i do that? Thanks for your help... take this question as a suggestion--- hint hint ;)
     
  4. eXmark

    eXmark Manufacturer / Sponsor
    Posts: 4,258

    Mac,

    Thanks for the added comments. Moving the tires farther apart really shouldn't change any rutting characteristics because the psi exerted on the ground doesn't change. Adding a wider tire can spread the weight over a wider contact patch and thus reduces the psi exerted on the ground. The key is the contact patch and not the tire width. As an example a smooth flat tire has a contact patch equivalent to the width of the tire. A Knobby tire on the other hand as a contact patch only as wide as the total cumulative width of each lug. I hope that makes sense.

    That being said actual psi of a 21" commercial mower is actually far greater than many zero turn riding mowers.

    I don't have the exact numbers for the Viking hydro but I would guestimate that if you took the average 200 lb. man and had him stand on 1 foot he would exert more psi on the ground than the average commercial mower.

    I've seen a few lawns that look to be rutted but upon further inspection there is either a discoloration to the lawn where the tires have crossed (usually caused by some missing nutrient) or it's simply the way the grass lays after the mower has passed over the lawn.

    Sorry, that was a little long winded but hopefully it cleared some things up. I will however pass your hints along for engineering to review.

    Thanks

    Terry
     

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