Has anybody tried running a 120/90 x 18 rear tire? Also, I see they are making radials specifically for bias ply bikes. I saw the Continental Classic Attack, for example. Any experience or advice would be greatly appreciated.
If I can not get the OE spec, inch sized tires, (4.00x18 for the rear) I prefer run the slightly smaller 110 metric size to attempt to avoid rubbing. I used to own a 1988 R100RS that came to me with a 120 on the rear, and the edge of the tire rubbed ever so slightly on the driveshaft side of the rear swing arm. I have used 120 sized tires on my R75/5 and it did not rub. The '88 RS was a rear mono shock model and that may have contributed to the interference. The tire profile when mounted may have been part of the issue as well. 110 tires are slightly smaller than 4.00 tires and 120's are slightly larger when mounted and inflated.
former Airmarshal, IL.
Thanks, James. My 1976 R90/6 has a stiffened San Jose aftermarket swingarm. I should probably just play it safe with the 110. It's not like the bike needs any more tire in terms of width. Thanks for your input.
there is NO benefit to running a bigger tire. some that big rub the swing arm. buy a good quality 400x18 , your not riding at Daytona
It is a bit challenging finding tires, in general. I am now looking for 110/90-18's for the street and also 110/90-18's for dual sport leaning towards dirt. I am helping a buddy with his 1983 R80ST which he will be riding on dirt roads and pavement up here in the VT NEK area. Any suggestions on tires would be much appreciated.
As Larry suggests, the 4.00 x18 is the O.E.M. tire size for your /6.
former Airmarshal, IL.
Bridgestone Battlax BT46 tires are available in the classic original sizes; 3.25x19 and 4.00x18 (H rated), and would probably be a great choice if you want to stick with the original.
Personally, I’ve been using “metric size” 100/90-19 and 120/90-18 tires for decades on my ‘78. I do have the slightly wider spacer on the rear axle to avoid the rub issue. Have used many sets of Dunlop D404’s, which are available and reasonably priced, and they last as well as anything else. I’m no Ricky Racer, so I don’t know if the wider rubber affects handling or not. Just seems practical.
There's NO benefit to running a bigger tire. Some that big rub the swing arm. Buy a good quality 400x18, you're not riding at Daytona.
The biggest difference you will notice is placing the bike on the center stand. A wider tire is also larger in OD, which helps you when you go to use the center stand. If you get too small the center stand may become unusable... especially if you are traveling with lots of luggage.
On the other hand, placing a shim on the axle to shift the rear wheel over 0.080" to miss the sidewall-to-swingarm scuffing does not deteriorate the handling.
The best all-around choice is probably the 4.00-18.... as long as it's not one of the square profile tires meant for use on Classic and Vintage show bikes.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
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