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  • Tire Identification

    I am often asked how to identify a set of tires during our weekly races and sometimes I just point them out as we specify tires for most classes. Then there was the time I accidentally dumped my well-labeled tire box...

    So, here are my observations on how to tell apart an assortment of tires.

    Rubber or Other?

    If the tires are on the car and you have the facilities handy, trying to sand the tires on regular sandpaper should work. Rubber tires will leave a pile of black dust while silicones will not. If the tires are not on the car, squeeze the tire as shown and try to slide it on itself. Silicone tires are far more likely to slide while rubber tires will grab.

    Front Tires:

    From Left to Right:
    The first two sets came on a Group C car and a GT car respectively, but as far as I can tell, they are the same and I measured them both at 18mm X 10mm. I like them as front tires as they fit nicely in the wheel wells without any modification, but I don't believe they are available separately. Their sidewalls are very rounded and the mould-parting line is on the sidewall.
    The third set is the PT07 19X10 Zero Grips, which are slightly larger than the stock fronts, so they may rub if the mould-parting line at the edge of the tread is not removed. The sidewalls are quite flat. The fourth set the PT15 17X10 Zero Grips, described by some as "rubber bands" as they have a really low profile with very flat sidewalls.

    Rear Tires -
    Stock Tires:

    From Left to Right:
    The first set is what came stock on Group C/GTP cars before the PT33 20X10 C1s were standard (the second set). The third set, with the "Firestone" moulded into the sidewall possibly visible, is what came stock on the 312PB and Alfa T33/3 cars before the C1s were standard (the fourth set). The fifth set is the C1s that come on the Chaparrals and GT 40s which, so far, are the only ones that are treaded. As far as I can tell, the first, second and fourth tires have come from the same mould, although the fourth set seems to have deformed slightly. They are fine when mounted. The C1s seem to stay shinier for longer and have slight radial grooves in the tread.

    F-Series Tires:

    The F-Series tires are the easiest to identify. The number is printed on the sidewall and corresponds to their Shore A hardness, with the F-15 the softest. (PT26:F-15, PT27:F-22, PT28:F-30 are 20X10; PT30:F-15 & PT31:F-22 are 20X11) They fit off-centre on the rib of the wheel as can be seen by more rubber on one sidewall than the other. This particular set was run for an evening on the Modena Slot Club's NINCO track.

    Silicone Tires:

    All five of's silicone tires are different, only four of which are still produced. The first three sets are all S1s and have the mould-parting line on the tread at the very edge, which takes several hours to wear off. The first two were both labelled PT03 20X12, but there are many differences. The second set was the original S1. It has a very round sidewall and is actually 20X12, while I have measured the first, with a more scale-appearing sidewall, as 19X11. The current PT03s seem to be a bit better than than the originals, but if that is due to a slightly different compound, the narrower width, or both, I do not know. The third set, PT06 19X10, looks to have been made from the same mould as the PT07 19X10 Zero Grips which are quite a bit stiffer and I haven't had much success with them. Then the S2s which have the mould-parting line on the sidewall: set four is the PT18 20.2X10.5 which came under the base with the GT cars before the C1s were standard and have a much lower profile sidewall than set five, which is the PT17 20X10 that came under the base of Group C/GTP and Classics. There were many PT18s mis-packaged as, or mixed with, PT17s, but that was resolved some time ago. The PT17 is our tire of choice. It runs well on wood or Sport track on large or small wheels, but if stretched over large wheels, will not shrink back to fit on small wheels like S1s will (unless left a long time). We have found PT18s to not work as well as PT17s on our tracks, possibly due to the lower profile. They can stretch and come off if mounted and demounted several times.

    GT Tires:

    From what I can tell, these three sets all came from the same mould. The first set is the original Rubber tire, the third is the PT18 that came under the base and the second is the current C1.

  • #2
    Well that clears that up Perhaps now I'll be able to sort out my own tyres!


    • #3
      Very comprehensive. I like it, appears to be a very useful tool you have just created. Thank you very much.

      Care to tackle NSR tires next?


      • #4
        it's about time someone posted something like this to help identify the different slotit tires available.
        I will have to go through my collection and reorganize them and lable them.


        • #5
          Maybe worth making this a sticky topic.


          • #6

            Anyone needing to organize P-series or NSR tires, sorry but you are on your own as I don't have any of either!

            I am working on a spreadsheet that I will add to the first post when ready.



            • #7
              Good grief, Kerry, that's a lot of work!

              As you found out things were about to spiral out of control with many tyres that were too difficult to tell from each other, so we've taken a decision: we have engraved, or are about to engrave, a small number on the inside wall of the tyre (where is engraved), on the box stock tyres, i.e. this applies or will apply to C1 and S2 tyres only.

              Said number is the ID of the drawing number that we use for a certain tyre.
              This is what we use as of today:
              1088 small front, classic (e.g. Alfa)
              1120 rear threaded (GT40, 2E)
              1121 front threaded (GT40, 2E)
              1152 new rear GT and Gr.C with 16.5 wheels (in the future this will only be used for GTs and all gr.Cs will wear tyre #1167)
              1159 GTs and grC front
              1140 Current rear Gr.C and classic for 15.8 mm wheels

              Note that some of these items may still not be available as spare parts, but will be in the future.
              Regarding 1140, not yet engraved. So, don't search for 1140 on the blue Alfa tyres.

              Relation between tyre number and code:

              PT20 1088
              PT32 1120+1121 (2+2 tyres)
              PT35 1140
              PT17, PT18, PT33 come from moulds that are not engraved

              I hope this helps. I am sure it will especially once the transition to this system is done.


              • #8
                that's excellent news, but why not just engrave the tire number onto the sidewall? - PT20 instead of 1088 - it seems like it would be much easier for the customer to cross reference a tire if the tire's model # from the packaging is printed on the tire instead of the code that slot it uses internally for their molds.
                Last edited by boopiejones; 08-31-2011, 09:54 AM.


                • #9
                  It had to be done...

                  Thanks Maurizio,

                  Glad to hear!


                  • #10
                    Glad to be of help...

                    Actually we may rearrange the codes to match the engraved number. PT20 is the commercial name, the important information is the drawing number and the compound, so for example PT20 may become PT-1088C1



                    • #11
                      That is GREAT NEWS..! an idea long overdue... looking forward to the spreadsheet.


                      • #12

                        Originally posted by View Post
                        Glad to be of help...

                        Actually we may rearrange the codes to match the engraved number. PT20 is the commercial name, the important information is the drawing number and the compound, so for example PT20 may become PT-1088C1

                        I would be more inclined to put the size of the tire in the code like for PT-33 it could be 2010C1 as it is 20 X 10 mm... that actually means something to the rest of us. The drawing number would necessitate carrying around another chart. I don't know if I want to open up another can of worms, but I can never remember what colour gear has how many teeth... plus the offset ones are all white. I use a Sharpie to colour every 5th tooth and then write the number on it. Each gear mould is unique anyway and adding a number after the website on the sidewinder and offset gears should be easy to do...


                        • #13

                          PT Fan knows all about the Slot.It PT's!!!!


                          • #14
                            Great idea!

                            Thank you VERY much, Kerry: great job! Identifying Slot.It tires was something that the CSI guys would have trouble with... before your contribution, of course!

                            Yo Maurizio, any kind/type of identification will be greatly appreciated. In this matter, I'm of the same opinion as Kerry about having the tire size imprinted along with it's commercial code. Oh! The part about the gear identification would be very nice too, specially the white ones.

                            Cheers and great Thread!


                            • #15
                              Post of the year!! I've often struggled with identifying tires. Well done Kerry.