Tube tires

[49worktruck]

Is there a SCTA rule reducing the speed rating for radial tires using a tube? I am running a ZR rated tire on a spoke rim and am concerned about pressure loss.  Same question for a shaved V rated tire to comply with a ZR rating.  Rule book only mentions tubeless bias ply tires can run with tubes.
Newbie

[Stainless1]

48WT, I've never seen radial tubes, so my guess is no you shouldn't do that.  Mixing bias and radial will probably create unwanted heat.... just my thoughts, not necessarily that of the racing organization...

[Milwaukee Midget]

Are we talking cars?

I drive an MGB with wire wheels, and I doubt very much that the rubber band that circles the inside of the wheel in and of itself would hold air for more than a day without a tube.  The MGB has radials and tubes, and while I don't race it, I've taken it on very long trips with no tire issues.

Chris

[dw230]

Why not contact a tire professional, like Roger Krause or Nat Jones. If they say adding tubes to radial tires is OK, ten take their advice on useage.

BTW, Nate Jones is always on site when the Speed Demon runs.

DW

[Jack Gifford]

... Mixing bias and radial will probably create unwanted heat...

You're apparently thinking of tubes as "bias"? A tube consists of a homogenous sheet of rubber with no "cords" , nor "plies", nor other reinforcements; so cannot have an attribute such as "bias-ply".

[JimL]

Bridgestone has a full line of Radial Tire tubes for motorcycles (you can really see the difference when you get one in your hands.)  These are for use with current type tires (not a "vintage" application).

  Check out what runs in Supermotard... I know the big KTM is 140+ stock, and probably more for the race prepped bikes.  I have no idea how that relates to running on the salt, or at even higher speeds.  If that's your speed range, those are obviously working well.  For higher?  don't know.

JimL

[49worktruck]

Running in the M/PG 1350cc class, record is 167+.  I'm just concerned about getting downgraded at tech if I run tubes in a ZR rated tire.  I think I'll just find a set of non spoke stock Harley wheels and leave nothing to chance.

[wobblywalrus]

I am not sure about tech inspection, but the combination of Bridgestone radial tubes, radial ZR rated tires, and spoked wheels has given me years of trouble free service.  Tens of thousands of miles of use, sometimes at high speeds, often with a full load of camping gear and a crab trap, and a bunch of runs at Bonneville.   

[fastman614]

Most tire manufacturers offer tubes for radial tires.... We used to use radial truck tubes in our drag slicks .... and we ran Z rated radial tires (with the tread "shaved") for 2 years on our Vega away back when... the owner of the local tire shop, who has helped me since forever it seems, gave me thw "low-down", if you will on the use of tubes.... the biggest concern is that, in usual street/road applications, tubes tend to be responsible for extra heat build up..... at Bonneville, though, with our air pressure in those radial tires being in the 65psi range, it was his opinion that the tire will not really be acting like a radial tire as the extra air pressure will tend to "stiffen" the tire and, since the tire is not being subjected to cornering, there is little, if any concern about the flexing usually associated with a radial tire and the resultant friction between the tire and tube actually causing any real amount of excess heat in a LSR application.