Super Rat tires

[viclioce]

So I’m looking for reasonable fitnent MX tires for the Super Rat. I’ve been fishing at Jpcycles, bike bandit, Dennis Kirk, rockymtnatv.
The Rat uses a 3.50 x 18” rear and a 3.00 x 19 front. Need a rear which will fit with the Rat chain guard in place. Where’s the best place to look??? Thx! Victor

[viclioce]

Is a 100/100/18 too big for the rear with the chain guard in place? Victor

[Dale]

Is a 100/100/18 too big for the rear with the chain guard in place? Victor

Yes

[Dale]

So I’m looking for reasonable fitnent MX tires for the Super Rat. I’ve been fishing at Jpcycles, bike bandit, Dennis Kirk, rockymtnatv.
The Rat uses a 3.50 x 18” rear and a 3.00 x 19 front. Need a rear which will fit with the Rat chain guard in place. Where’s the best place to look??? Thx! Victor

Double check the rear tire size. The specs for the 93 Super Rat lists 3.25x18. However all three models (93, 93A & 93B) show 3.50x18 in their parts lists?

If 3.25x18 is correct then good luck. If 3.50x18 is correct then I would search for the new Dunlops in 3.50x18 or the Cheng Shin 4.10x18.

[taber hodaka]

All three of my original parts list for the 93, 93A & 93B shows all the model 93 super rat's using a 3.25x18 rear tire. ----------Clarence

[viclioce]

So which tire size is the closest to a 3.25 x 18? Would it be a 90 cm width? An 85? And who is the Hodaka Days sponsor who someone said is making tires which fit again?

BTW, the current Nitto on the rear wheel is a 3.25 x 18” Victor

[Dale]

I don't think you will find any new knobby that would be equivalent to 3.25x18. New old stock is the only option.
My best advice would be to buy the narrowest 18 inch tire available and be prepared to trim the side knobs. That tire would be the Cheng Shin 4.10x18.

[Bullfrog]

. . . which reveals the "looseness" of the size designations on motorcycle tires. (Rhetorical question follows.) Why is it that a tire labeled as a "4.10" (four and one tenth inch - nominally) is actually about as close as you can get to a "3.50" (three and one-half inch - nominally)? This seems to be one of the mysteries of the universe. But it sure increases the value of discussion groups like this.
Ed

[taber hodaka]

100/100 the first number the hiegth of the tire in mm the second number is the width in mm. so the second 100 divided by 25.4 equals a width of 3.94?? A 100/90 would be 3.54 inches wide. A 3.25 tire would be about 82.55 mm wide, is my math correct?? --------------- Clarence

[JPark]

I think the .10 was an early system to designate a lower aspect ratio tire. So a 4.10 was a 100/90 which was 4.00 wide and 3.50 high. There was a 3.60 that subbed for a 3.25. At least that was my understanding and observation on road tires of the day. It was a totally loopy system that was thankfully abandoned for the wonderful 'metric' system in which the rim diameter and width is still in inches and the tire is in millimetres. Car tires are the same and the public just assumes it must make some sense somewhere to somebody.

I've also found that the sidewall numbers can reflect the casing width or the knob protrusion width. Then you inflate the thing and it expands out to something else again. Plus the final width depends to an extent upon the rim width.

Given the low weight of a Hodaka I'd be careful of using too heavy a tire for reasons of rotating mass and also unsprung weight. Overly stiff casings don't help either. The tire is the first part of the suspension system. Something appropriate for a 250 lb bike with a 200 lb rider may be less so for a 150/150 combo. Fitting the most tire you can get inside the swing arm is currently fashionable but not usually so effective.

[dirty_rat]

We always ran 3.50x18 rear tires on our Rats back in the day without any clearance problems. They did come stock with 3.25x18 rears, but no one seemed to carry them as replacements so we just went with the 3.50's. As noted on facebook there are Barum 3.50x18 tires listed on ebay for a good price and they last almost forever.

[taber hodaka]

yes ebay has 3.50x18 tires listed and 3.75X17. I still have not caught on to the metric tire size I am not smart enough to learn and seems nobody is smart enough to help me understand it. I generally can raise the IQ level of any group of people setting at a table and it is easy I just get up and leave. -------------- Clarence

[Dale]

I generally can raise the IQ level of any group of people setting at a table and it is easy I just get up and leave. -------------- Clarence

I am going to remember this one!

As for the metric sizes; it seems that each manufacturer does there own thing. Even though there are charts that list cross references, the actual sizes vary. In addition, I believe that the width number is regarding the carcass and has nothing to do with the outside dimension of the knobs. This is why a 3.50" knobby measures larger if measured knob to knob. Trial and error. I have been in the pits of many vintage races over the past several years with my digital calipers in hand. I've requested permission and have measured every brand of small bore rear tires that I have come across (this does not include a Barum by the way). This includes metric and standard. Of the ones that I have measured, the Cheng Shin 4.10x18 is the narrowest.

[matt glascock]

I run the Cheng Shin tires on my 93B Super Rat. They have held up extremely well over 20 or so motos and a few dozen hours of fun riding/trailing. Great tires and no fitment issues with the chain guard in place.

[viclioce]

Matt. Which specific Cheng Shin, and where did you buy them? Victor

[socalhodaka]

C755 is what I have on mine. 350/18. This is the one they don’t make anymore.

[ossa95d]

I have C755 4.10-18 Cheng Shins on both of my race bikes. Very light and fit and wear well. Duro also makes a 4.10 that is comparable and Dunlop has a vintage small knobby set that looks even better but I haven't tried them yet. I have all three options here in stock at my shop and they should be available for order at any motorcycle dealer.

[viclioce]

OK. I bought a Cheng Shin C755 4.10 x 18 rear & a Dunlop Geomax MX53 70/100/19” front, along with tubes & rim liners. Tuesday arrival for $10 shipping. Same shipping price as the other arriving on Thursday. I’ll have my son in law help me mount them. Not bad for $132 total with shipping. DennisKirk.com had them both for under $50 each.

I want to thank everyone for their input on this. I know the rear Rat tire can be an issue! And thanks to Dale for the actual measurement information! Really gave me piece of mind in a rear tire choice!

Usually tire discussions are like oil discussions. Everyone seems to have their favorite. But in this instance it really does come down to which tire fits, and as Dale demonstrated there can be a big width differences between tires bearing the same size within differing brands! Thanks for all the great advise!!! Victor