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Discussion: Archives > Siping
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   I thought the discussion about siping merited its own thread.

   I did a little research (googled "siping tires"), and here's what I found:


      1)  Increased traction on packed-snow and ice for all-season and dry weather tires.

               It does.  This isn't controversial even among skeptics.

      2)   Increased tread longevity.

               I was unable to find any data to support this claim. 

               (Update:  The Tire Factory claims that siping increases tread longevity by 15-20% based on tests conducted by truck and bus fleets.

      3)   More even treadwear.

               I was unable to find any data to support this claim.


      1)   Decreased performance in wet and/or dry conditions.

               I was able to find one study (Consumer Reports) that showed an increased stopping distance in wet and dry conditions of "a few feet" for two models of one manufacturer's tires.

               Otherwise, there is no data to support this claim.

      2)  Decreased tread longevity.

               I was unable to find any data to support this claim.

      3)  Irregular tread wear.

               I was unable to find any data to support this claim.

      4)  Tread damage.

               There's some anecdotal evidence that siping tires with lug-tread patterns can cause damage to the lugs that would not otherwise occur.

               I was unable, however, to find any tire dealer that recommended siping tires with lug-tread, such as snow tires or off-road tires.

      5)  Increased rolling resistance.

                  I was unable to find any data to support this claim.

      6)  Siped all-season tires to not perform as well as snow tires on packed snow and ice.

               I was unable to find any data to support this claim.

      7)  Siping voids the manufacturer's warranty.

               Generally true, although it depends on the manufacturer.  Some will still warranty their tires, but not if the damage can be attributed to siping.

               In any case, dealers that offer siping also offer their own warranties.

My experience:

   A little more than a year ago, I purchased a set of Toyo Open-Country HT's from Les Schwab in Wilsonville, Oregon, to replace the Goodyear Wrangler HT's on a 2004 Honda Element EX AWD.  I had the tires siped.

   The first thing that I noticed was a decrease in fuel economy of about 1 mpg.  I'm not able to say whether or not this difference is the result in the change of brands or the result of siping, but it may offer some evidence that siping does indeed increase the rolling resistance of a tire.

   I noticed better traction on packed snow and ice than the unsiped Wranglers.  I didn't notice any difference in performance in the dry or wet.

   Les Scwhab offers a warranty of 65,000 miles for these tires.

   The Toyos started with a tread depth of 12/32's.  At 60,000 miles, the tread depth was 7/32's in all grooves on all four tires.  The treadwear was dead even and, if I take them all the way down to 2/32's, on pace to get 120,000 miles.

   I check tire-pressure monthly (34 psi front, 32 psi rear) and rotate at 10,000 miles.

Anthony Knox


Edited 11/12/07   by  Anthony_Knox
2 of 11

Thanks for posting this.  As with all things in life, there are pros and cons, and it's good for folks to have the information up front, and understand the compromises, before they take action.

Regards, Jason

3 of 11

I also wanted to comment that it's "unfortunate", in terms of a direct comparison at least, that you had the new tires siped before you had a chance to run them.  In other words, you said that you noticed a decrease in fuel economy, but didn't know if that was due to the siping or the change in tires (I bet on the change in tires, as OE tires often excel in rolling resistance).  You also said that you noticed an improvement in packed snow traction, but I'd wager that it may also be due to the change in tires (as OE tires are not often praised for their winter weather performance).

It is true, unfortunately, that there's not a whole lot of data out there to support or refute claims of improvements due to aftermarket siping.  There are many outfits that claim improvements (but of course, they also do the work, so they have a motive here).  And as you say, few manufacturers are going to recommend or endorse modifications to their product, seeking to improve its performance.

In the absence of good data either way, I guess there will always be folks who think it helps, and there will always be folks who don't, and I guess that's just fine.

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Siping is more "added value" silliness from tire dealers.  If the tires could be improved that simply don't you think the tire maker would be cutting the tread that way from the factory.

Now excuse me while I change the magnets on my fuel line (for better fuel economy) and rotate the nitrogen in my tires....
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There's nothing in your post that adds to the discussion about siping, and nothing worthy of a response, so I'll just refer you to my reply to your post in "best place to buy tires?".
6 of 11
Of course my post adds to the discussion of siping.  It exposes it as more silliness from the tire dealers.  As I stated previously, if siping did so much to improve the tires don't you think the manufacturer would design the tread that way?

Or put more eloquently, do you think the tire makers deliberately sell a tire that is not as good as it could be after millions of dollars of R&D?  This is the same argument people use to support their use of "the vornado" and fuel line magnets to improve fuel efficiency.

Your statement referring me back to the original post is disingenuous at the very least since you spent over two pages discussing the relative merits of siping.  Just because my point of view is different than yours is no reason to open a can of you-know-what on me.

Regarding the original topic, I prefer or else I go to BJ's Wholesale Club.  Either way I get great prices albeit more limited selection then some other places.
7 of 11

I think Robert has a point:

If such a trivial alteration in tread is so beneficial, why haven't manufacturers already done this?

8 of 11
   I think if you read my original post in this thread more closely, you'll see that I never expressed an opinion about siping and never recommended that anyone else do it.  I shared the results of some Web research, and I related my own experience.
9 of 11

   I can think of three reasons:

      1)  No mass market for siped tires, at least the kind of siping we're talking about.

      2)  Siping adds cost and manufacturing time.

      3)  Manufacturers have an obvious financial incentive not to engage in, or recommend, a tire modification that offers a year 'round alternative to snow tires.


11 of 11
Thanks Gene.  Would you be able to post the raw data (stopping distance comparisons)?