Front 3.60 vs 4.10?

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Matt Spencer said:
Perilli ? well . . . ,. if someone saw the $ 20 Perrili's , and was somewhat tempted . They Might THINK TWICE ,
Theyre actually hilerious to ride on , but if tarmacs involved , frorget it .

3.60 Vs 4.10 .

Well , RACING , you tend to be ' On It ' , If its the Classic ' Run the Bends ' fine .

The ' Trigonics ' though , tend to be tip toey , and follow seams etc in the tarmac , and cambers to a degree . Depending on the cycle . ( The Home Built Triton was good ) the 3.00 KR 76 empacises this .
However ,
If youre a ' Run it into the bends on the front ' , ' pushing ' the largers a better bet . The C'do with 3.00 KR 76 F & 4.1 K 81 R , no idle - Theres a r h off camber with a kink left to Sq on the downhill main road .
Holding a tad of throttle & some brake , in the wet the Front & Back would push . Due to the right lock for the off camber .
Another off camber Rt always seemed slow , trying not to be , it'd always drift ( slightly back out - but cranked over always both ends would be drifting . NOT one end slideing . So Triton Frame was designed to
do Both . If you brought the throttle up , in a drift - it'd transition to a slide . A bit safer . More Control .)

So , the idea is to get a Commando to do likewise , without flapping all over the place . Even if the road is a bit uneven . ALL the Highways were CHIP SEAL GRANIT CHIP . And after a year UNEVEN .
A freshly reealed road was usually past round as ' worth a ride ' , even if far off .

A ' Racing Posture & Clambering around the plot , arnt quite the same as wedged in two up with luggage . Thus ' Riding Style ' and tyre choice are interelated . High mile touring Id go for big rubber &
TRACTION .
Sharp Steering gets wearying on other than first class surfaces . So local roads'd be relevat too .
AND see the preservatives scrrubbed off . A 1400 Kwacker ended up on its side on the turn onto the road on new tyres . Temp. zero . A grand or two of trinklets down the drain .

If you were stropping it, solo . The Narrow front is precise . But Downhill pushing the frontthrough the turn entry ( to apex ) as some are want , wont on a widdle fing . Itll tend to wobble .
Unless you throttle it & dfrift in . Which might be somewhat unlikely on the road . There being old pilots & bold pilots , but no ol;d bold pilots . Tho theres a few full of metal from ' the Track '
if theyve been caught out .

So , Generally , TRACTION is KING , for on the ROAD . And I should think the front should stay adhered in the not so unlikely event of a emergency brake and steering input . Perhaps past the limit .
Like your fine tne race chassis balance . But with semis , dogs , here wombats and roo's on the course . NZ the only mobile chicanes are man made . So the skys the limit . Aus theres Roo's so limits sane .
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OEM front tyre on 700lbs dry of ST1100 Pan European (non ABS) is a 110/80 18" Bridgestone.

The Pan wears the front first, which should not be a surprise with all that weight behind it. Case for a big oversize tyre, surely? No. This is the best tyre for it. By far. And I tried a few.

One up, two up, two up with 2 weeks of luggage in the mountains. Steering is light touch countersteer only.

Even if you think it works, it doesn't, you don't want to be weight shifting for a 400 mile day two up with luggage in the mountains.

Steering degradation/contour tracking only appear when the rear wears square.

'Sharp' steering is the product of incorrect steering geometry! Or more often, the rigid arms and excess steering inputs of a nervous and/or tired rider. Relax.

People seem to think big tyres look cool and must be 'better'.....

Bigger rear tyre is only a solution to a point. Which is normally when it starts to slow steering and turning.

Bigger front tyres are rarely the right solution to anything.
 
I use a 90mm (3,5 inch)18 inch tyre on a WM3 rim on the front of my Seeley and a 100mm (4 inch)18 inch tyre on a WM4 rim on the back. The handling is very nimble. But I always align my wheels with a string line. Even when you do that, the sides of the front and rear tyres do not align when you have different size tyres front and back.
Can you still buy decent 18 inch tyres in the UK in those diameters ? A while back there were race compound TT100 Dunlops in the right sizes.
 
Slow steering is often caused by steering geometry, rather than front tyre width. When the first Commandos chucked a few inexperienced riders down the road, I suspect Norton reduced the amount of trail by increasing the yoke offset, when an hydraulic steering damper would probably have fixed the problem. Where the front of the bike sits as you brake into corners determines how the steering feels. With a Commando, the rake would only have to change by a poofteenth to make the steering feel heavy.
If you have a lot of trail, you can have the bike becoming unstable at high speed, so you need the damper. But with a lot of trail the bike stays more upright as you turn into corners, so tyre width is less of a problem
On my Seeley, I use a 90mm tyre on 18 inch WM3 rim on the front with 100mm tyre on 18 inch on the back. It has about 106mm of trail on the steering. I flick it into corners while braking, then immediately gas the motor very hard. The bike self-steers in the direction in which it is cranked over. You could not do that with a road bike, you would neck yourself regularly
 
The original post was about road going type riding. Most of us are at that level. Most of us aren't as willing to push things as we once were. All that nice paint might get road rash if we fall down. What I want to know and I thinK the first poster wanted to know was "what is the best front tyre" which of course has no answer. What can be answered is what tyre width is best for our
skinny standard rims. Will the 90-90 be the best all around road tyre or do we go to the 100-90 (4.10) size?
...not forget DOES IT REALLY MATTER and will us punters ACTUALLY NOTICE?
 
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When I bought mine it had 10yr old 3.60 TT100s front and rear. I replaced with 2 x 4.10 TT100. It required more effort to turn in. It was very noticeable.

As an aside, after 4,000 miles, I still have 6mm tread on the front, but only just under 3mm on the rear and starting to tramline.
 
Onder said:
The original post was about road going type riding. Most of us are at that level. Most of us aren't as willing to push things as we once were. All that nice paint might get road rash if we fall down. What I want to know and I thing the first poster wanted to know was "what is the best front tyre" which of course has no answer. What can be answered is what tyre width is best for our
skinny standard rims. Will the 90-90 be the best all around road tyre or do we go to the 100-90 (4.10) size?
...not forget DOES IT REALLY MATTER and will us punters ACTUALLY NOTICE?
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There is also the variety of widths in the one size - 100/90 (19) vary from 100mm (Bridgestone BT45 - no longer sold) up to 111mm (Michelin Road Classic).
I opted for Avon Roadrider Mk2 - 109mm

Pirellis are 103mm (as is Bridgestone BT46) and Metzelers are 106mm
Cheers
 
Rears have a short life on any older brit bike unless you run square section tyres like the K70 or the Avon Speedmaster. TT100 go very quickly and modern round profiles wear down almost as fast. For the average rider, not the fellow who has worn off the ends of his footrests, the middle of the tyre will be long gone before the outer edges show much if any wear.
I must say I have not tried the BT45 or 46 multicompound construction type and perhaps worth a shot.
Edit: And it can be down to what seems best for each rider. Reminds me of the fork oil situation: no standard for viscosity and tyres seem to have no standard for rims or actual tyre size.
 
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Onder said:
Rears have a short life on any older brit bike unless you run square section tyres like the K70 or the Avon Speedmaster. TT100 go very quickly and modern round profiles wear down almost as fast. For the average rider, not the fellow who has worn off the ends of his footrests, the middle of the tyre will be long gone before the outer edges show much if any wear.
I must say I have not tried the BT45 or 46 multicompound construction type and perhaps worth a shot.
Edit: And it can be down to what seems best for each rider. Reminds me of the fork oil situation: no standard for viscosity and tyres seem to have no standard for rims or actual tyre size.
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I totally agree that it is down to what feels right for each rider - but the manufacturers do have recommended rim sizes for their tyres.
I made the following spreadsheet when making my choice.
May be useful to some?
Cheers
Screen Shot 2022-04-16 at 8.24.00 pm.png
 
I use Avon tires but on stock Commandos, 90/90-19 front because that's the biggest Avon specifies for WM2 rims and 100/90-19 rear since 90/90-19 is front only. I really wish Norton had used WM3, at least on the rear and when I get around to it on my rider I'll do that. Part of the problem is that Avon says 90/90-19 is front only and requires WM2, WM3*, or WM4 rims, but 100/90 is front or rear but requires WM3, WM4*, or WM5 rims. So there is no way on a stock Norton to actually use the same Avon tires front and rear within the Avon specs! With WM3 or WM4 rims front and rear you can use the Avon F/R 100/90-19. *=Avon Recommended.

IMHO, when you put 100/90 or larger on WM2 rims you are changing the geometry of the tire enough to cause them not to handle as designed but the lessor of two evils is the rear for normal dry-road riding and stopping.
 
I put a WM3 19 on the back of mine. 90-90 look awful small compared to a stock TT100 4.10 Dunlop.
Avon used to make a clone of the TT100 4.10 but in actuality is a lot skinnier. I have one somewhere I can
measure it tomorrow. I too worry about braking with a 90-90 as well as washout on the lanes.
No TT100 in your database? Be good to see how they compare even though I realize they are old hat and especially so for Interstate touring work.
 
Another option if you choose TT100's is to fit a 410x19 on the rear and a 100/90x19 TT100GP on the front, the TT100GP is narrower and softer than the 410 but is not an option for a rear for road use I have used this combination on my previous Mk2A.
 
robs ss said:
An Avon Roadrider Mk2 (100/90) up front feels good to me - but might have to try 90/90 after @ntst8 's comment.
Could you elaborate on what was different?

Here's the Avon data on the two:
View attachment 85474
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ntst8 said:
It just turns in with less effort, more like a featherbed for turn in - but even with a DT head steady still not as planted once in the corner.
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I wouldn't put the sharpness down to just width, as the 90/90 has an inch less rolling diameter so will decrease rake and trail.
 
marshg246 said:
I use Avon tires but on stock Commandos, 90/90-19 front because that's the biggest Avon specifies for WM2 rims and 100/90-19 rear since 90/90-19 is front only. I really wish Norton had used WM3, at least on the rear and when I get around to it on my rider I'll do that. Part of the problem is that Avon says 90/90-19 is front only and requires WM2, WM3*, or WM4 rims, but 100/90 is front or rear but requires WM3, WM4*, or WM5 rims. So there is no way on a stock Norton to actually use the same Avon tires front and rear within the Avon specs! With WM3 or WM4 rims front and rear you can use the Avon F/R 100/90-19. *=Avon Recommended.

IMHO, when you put 100/90 or larger on WM2 rims you are changing the geometry of the tire enough to cause them not to handle as designed but the lessor of two evils is the rear for normal dry-road riding and stopping.
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That is correct Greg.

However, when you type Norton Commando 850 into the search function on Avons web site, it brings up the 100/90 19 Roadrider and the 4.10 19 Road Runner. Both front and rear.

So Avon are basically offering conflicting info here !

Plus, we know that many folk do use the 100/90 front and rear and swear by that combo.

The Road Runners are stated as suitable for 1.85” rims. I never liked them much back in the day but they are now described as being of modern compound and construction, so I’d imagine they are good tyres ?
 
Stock tyre on the S2 750 Enfield was a 3.50 Avon rib on WM2-19. I took this off and put the front end of my Commando 850 on it with the 4.10 TT 100. It is noticeably slower to turn but it actually feels more secure to me.
I sort of like a heavy feel in the front otherwise I feel like I'm riding an old 350 Honda twin.
 
Fast Eddie said:
That is correct Greg.

However, when you type Norton Commando 850 into the search function on Avons web site, it brings up the 100/90 19 Roadrider and the 4.10 19 Road Runner. Both front and rear.

So Avon are basically offering conflicting info here !

Plus, we know that many folk do use the 100/90 front and rear and swear by that combo.

The Road Runners are stated as suitable for 1.85” rims. I never liked them much back in the day but they are now described as being of modern compound and construction, so I’d imagine they are good tyres ?
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FE, yes the website does confuse, but in Europe motorcycle tyres and rim size generally adhere to the manufacturers body ETRMA. For radial (do not confuse with radial ply) you can go one rim width up or down from the tyres designed rim width, with radial / cross ply, 2 rim widths up or down. This can be extended but the manufacturer has to pay to get the approval. Like most things when you move away from the ideal, it may still work but will be a compromise.

Some of the more modern tyres are not designed to sit against a WM rim, so be wary of this one as well, thankfully these are usually the newest tyres applicable to specific bikes.

Some of the data above is interesting, hardly any difference in the width of 3.25'' against the 100/90 widths.
 
I have a RR 100-90 19". The sticker applied to it says "3.50 x 19".
 

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