Using Racing Tyres on the Road

[Monkeypants]

Ed, the 100/90/19 Roadrider works well on the Standard WM2 x 19 Rear wheel, however , I did find it is overloaded when riding two up with luggage, unless the riders are very tiny people and the luggage is very light.
It comes with a 57 load rating, which I recall is about 540 pounds. With our Rapide loaded and two of us on it,the rear wheel has over 700 pounds load, that is why I finally switched to WM3 rims and the 4.00 x 18 rear . The 400 x 18 has a 64 v rating, still not adequate, but closer to the mark.
The other benefit with the larger profile tire is increased tire mileage and a little nicer ride. As compared to the stock skinny tires, the bigger profile front and rear take a tiny bit of additional effort to initiate turns, but the rider adjusts to that quickly.

 

[Monkeypants]

Misinformation on my part, I just looked up minimum rim sizes for the 100/90/19 Roadrider and it needs a WM3. No doubt you can mount one on a WM2 ( I did) but the profile and contact patch is not correct according to Avon. I suppose if we trust them to design and build our tires then we ought to try to follow their rim recommendations

Glen

 

[Marcus Bowden]

Before going to sea I was using ribbed WM1 20" front and GP WM2 19" rear, changing rear every two to four thousand miles, always felt squiggly but secure as rim I think was too narrow for tire, then swopped the front wheel for an ally WMI 21" which always felt better, Now running WM3 rim ? 21" front 90x90 and WM4 rim 18" rear 400 with Avon Distanzia on their recommended rim size, recently they have dropped the 400 size but do a 410. 5mm wider can I get it in !or the next change ? I like the 10.5 mm tread as the present one has done 8k+ and still good for another 2k minimum. Thats on the "B" banana bike. The "A" is the same on the front WM3 x 21" and WM2 3.50 x 19" rear want to reduce to 18" and the bigger tyre but chain/chain guard is almost touching now ! Any tried an 18" on the rear of an "A"
bananaman

 

[Magnetoman]

IHowever they are listed as not for road use and I guess would void your insurance if noticed during any accident.

Although some of the other posts skated around this point, this seems to me to be the key issue to consider even if race tires were in every way "better" for your use on the street. In a minor accident it's unlikely anyone would look at your tires. However, if you were in an accident where serious property damage, injury, or death were involved, your insurance company's accident investigator would be looking for any reason they could for them to avoid liability and to transfer it all to you.

Although you might pay to have a technical expert testify that "racing tires" weren't the reason for the accident (at $300-500/hour, plus expenses, for his testimony), even a first year lawyer should have no trouble convincing a jury that an irresponsible motorcyclist who fancied himself a racer was riding recklessly, as evidenced by his use of "illegal racing tires." Jeez, having just written this, I'm ready to convict you...

Anyway, it comes down to a personal benefit/risk analysis. Is the potential performance benefit of the tires outweighed by the potential risk, albeit small, of using them on the street? If so, go for it.

 

[Magnetoman]

p.s. my brother-in-law owns an independent insurance investigation company. I haven't asked him about tires (but now I will the next time I speak with him), but he has a masters degree in mechanical engineering and from the details of the many cases he has investigated over the past 20+ years I very seriously doubt he would miss the lack of proper certifications molded into the sidewall. Further, I would be surprised if he didn't check the batch number on the tires to see if they had been subject to recall, were out of date, etc. This is the sort of thing he would do as a matter of routine even if it appeared the accident had been caused by, say, a broken brake cable.

 

[BigEd]

What size are your rims and what size tyres do you use?

Interesting to read Glen's comments. My tyres and rim sizes certainly don't appear to match recommendations.
My rear tyre is an Avon Roadrider 100/90 x 19" and is fitted to a WM2 rim. The front tyre is a 90/90 x 19" on a Dunlop alloy rim marked WM1 (2 1/4) x 19.
The front rim is definitely on the narrow side for the tyre but the bike steers and handles well. I'm not suggesting that it is an ideal setup but it has worked without any problems for a lot of miles. The wheels used are those that came in the basket case from which the bike was assembled. When funds are available the wheels will be rebuilt with probably WM2 front and WM3 rear rims. It will be interesting to see how different the tyres feel on wider rims.

 

[TouringGodet]

I too do not care for SM rear tyres. I have a Bridgestone 19" front/rear pattern tyre on the rear of the Shadow, mostly because I bought the exact same tyre for the front of the Comet, since the Comet has proper Touring spec rims. Every time I took the Shadow over to Haig's shop (a local Vin guru in So Cal), he would make a remark about how could I ride with such a skinny tyre on the back. I think it is a 100/90, but would have to take a look to verify.

I used to use Avon RoadRunners, I think that was the model name, on the rear of the twin, but got tired of the lousy tread life, got sick of buying and changing tyres often. The Bridgestones last longer.

 

[vibrac]

The moto guzzi V8 ran on a 3,50X 19 (however perhaps thats all there was back then).
I may have said this before but at a track day I was running in the comet (18" 110/80) racing Avon's and on slow corners I was passing all the crutch rockets as they wallowed round the rolling radius of their huge tyres laid almost horizontal to the ground while I fairly upright had the power on from the apex. Unfortunately the effect only lasted for a few yards but it was enough to cause visits during the afternoon by curious riders who had ignored the funny old bike in the morning.
I also have also attributed a lot of the success of Ben on his C15 BSA to the fact I ran a bantam back wheel with a narrow tyre, (It also showed me that fashion is not confined to the catwalks as slowly all the other C15's got skinnier tyres!) I think the basic rule is if it ain't got the power you don't need the rubber.

 

[Rob H]

What about using a 360 / H / 19 Dunlop k81 TT100, anyone have any experience of using this with the avon speedmaster 300x x20 front?

 

[Kansas Bad Man]

Back in the day , around 1952, the Otaways hear in Wichita built two two smokes H.D.s a 125 and a 165 , called them the SPOOK and SUPER SPOOK. they used the heavy duty tires off one of those three wheel peddle tricycle delivery carts. they looked to skinny to work but did. Did at least for these 14 year old eyes , looked blinding fast around the corners. kind of parrots what vibrac found out.