TT100 - Rain grooves

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Dec 13, 2004
I am in the process of getting my 74 Interstate/Roadster (?) back on the road, after a 19 year rest in a, mostly, dry - though unheated - garage. I am well on my way, but, currently, delayed by the temperatures here near the central USA/canadian border.
I have, recently, replaced the 20+ year old tyres with new - Japanese made - Dunlop TT100's. I never questioned the selection of the replacements, as they were original equipment when new - here, anyway.
I have, however, recently, read comments about their sensitivity to rain grooves. In the day, rain grooves were not too prevalent, but when encountered, damned near put my pants afloat. I avoided them at all costs. A run near the ton, one evening, comes to mind when I hastily exited the motorway to avoid a rain-grooved curve - nearly losing it trying to stop. No problem with the tyres, but too great of expectations from the brakes. It was a close call, and, from the exit, was a sobering, figuratively, ride home from there.
My question is, are these tyres as dangerous as they feel on the rain-grooves, or should one just carry-on riding and try to avoid being disconcerted by the wiggles?
In this area, the practise of grooving the roads is, now, wide-spread.
The drive to my girlfriend's labor-camp, on the motorway, is about 125 miles. It is mostly rain-grooved. It takes me about 1.5 hours to cannonball in my car, but, taking secondary roads on my Royal-Enfield Bullet takes nearly 4 hours! The thought of having, now, re-shoed with new TT100's, enduring 1.5 hours of white knuckled riding fills me with dread. Am I foolish in my concerns about the wiggles? The Commando's, that is, I can deal with the girlfriend's.
Best regards,
My bike has TT100's also and it wiggles in the rain grooves too. I always ran them on my old 850 years ago and as I recall it wiggled a bit in the grooves too.

It actually feels worse than it is. You can just stay loose, let the front end seek out its own line, and not worry about it for the most part. Kinda like riding a dirt bike in a sandwash.

Alternatively, a more modern tread pattern without the grooves (like the Super Venoms) is said to help. I need to get new tires soon so I think I'll try a set.

Chugley has Avon Speedmasters with a ribbed front tire but only has the slightest hint of a wiggle. Of course he doesn't go as fast :)

TT100 tread in rain grooves


The TT100s definitely like to track the rain grooves. Avon Roadrunner (old style) also does this to a lesser degree. I now have as Debby mentioned Avon AM18 100/90x19 Super Venom rear and AM20 90/90x19 Roadrunner (new type) front now and no wiggle from these. They stick better too. If you're a former dirt rider, me too, the wiggle probably won't bother you that much.

Is the 100/90 too wide for the front? I think I read something about that somewhere...


Hi Debby,

No the 100/90x19 is roughly the same as 4.10x19. It was suggested to me to use the 90/90x19 to improve the steering which in my opinion it stears too easily, feels unstable. When this one wears out I'm going to the 100/90x19 so will use AM18s both front and rear.
Know what this sounds like to me? Many years ago, my bike was VERY sensitive about going over those metal grates in bridges, and rain groves on the highway. Turns out the isolastics were not in order and the bike just wasn't able to keep a straight line. I haven't had any nervous moments now for years, since I plain took care of the isolastics. If you bike is so sensitve, check out those things. I run TT 100s too and my problem wasn't the tires.
Well, same thing on my bike as it turns out. The wiggling was pretty bad with the loose isos and swingarm pivot, but with that stuff nice and tight the wiggles greatly reduced. I rode the bike over the rain grooves recently and decided I can live with it. So I just ordered a new set of K81s. I like the tires, they're "period-correct", and they wear longer than the venoms too.

Les Emery (Norvil, England) tells me if my bike handles good with the TT 100s, that I will be even happier with the venoms...thats a lot of money though, to spend when my TTs are still OK and I feel good with them...but according to him, and I suppose he has a bit of know-how....the Venoms are better. Lord knows...if I come into a rich uncle's estate, I might change the both tires and try, but as it is, the front TT lasts through at least four rear tires, so since the front is almost will be a while before I get up interest to remove perfectly good tires and put others on, just to see what the difference is...maybe someone out there has a few comments though, someone has to have an opinion.....let er rip! Best! Piperboy

PS....what this about the TTs lasting longer than the Venoms? My TT in back doesn't last more than two summers, if I'm lucky....and a qiuck trip to England from Germany will eat up a rear tire long..or short... do these Venoms last?????
My last two rear tires have been Super Venoms, got about 3000 miles each.
piperboy reunplugged

Thanks...sounds like about what the TTs last. I haven't tried the Venoms, but I am satisfied with the TTs, when they are new. If you notice, tires will wear flat in the middle of the tread, can't change that, but when too flat there, you can really notice the point, when you lean into a corner, between the flat middle of the the tread and the nice rounded side area of the tread, it can surprize you and suddenly cause the bike to lean much further over...therefore I change the tires when I see the rounded profile is getting flattened out too much. The TTs are though, really nice to drive with when they are new and have that nice rounded profile...are the Venoms are really much better? You must have tried both....or?
After extended use holding a dust cover off the garage floor my Norton has only be back on the road for the last couple of years, with a few pauses over that time while various bits have had a birthday. So its a while since i rode it on anything else.
The 3000 miles is taking the tread down to virtually nothing in the middle.
Supervenom vs TT100

The comments about both tires are what I have experienced. If you need to replace tires the Supervenoms are cheaper and handle a little better than TT100s, but wear a little faster.

The tires that were really bad on rain grooves were the original fitment Avon GP. Good thing those aren't available anymore. They came on my first Commando, a new '72 combat roadster I drove on the southern California freeways in '73.
I used to get 5,000 miles or better from a rear K81 in the old days. I found some maintenance records from the old bike and the last rear tire I replaced lasted 5,500 miles. Don't know if the new ones get similar mileage but I'll find out soon. Obviously, YMMV currently has K81s on sale at a very attractive price. I ordered a set last week and they just arrived. They're sitting in my office as I type :) I saved $60 USD over what a set of venoms would have cost. Can't complain about that! :D


Dunno 'bout K81's. Seems like the SuperVenoms are better for knee-dragging than the Dunlops:
TT100 - Rain grooves

And, they just didn't seem that pricey next to the MkIII rear hub, caliper, rotor and master cylinder. :wink:

Oh I'm sure they're great tires but something about them just doesn't look right to me. I don't know, too modern I guess.

As for the knee dragging, at my age that would be purely unintended and probably accompanied by elbow dragging and shoulder dragging too! You know what they say - there's no old bold pilots.

Anyway, you'll be grinding away at your sidestand, your centerstand, and your footpegs long before you reach the limits of the K81s. Been there done that.

my .02,
Debby and cycled

Dumb question here....I am seeing that supposedly the venoms hold the road better and such.....but how can we tell how far over one can lean in the corner with one type of tire or the other.......Debby has a point. My bike will scrape the side or centerstand before it ever comes to the point where it drops out from under me. I back off, then, if I feel something scraping. It may be all well and good that the venoms can be leaned over further than the TTs, but the deciding factor as to how far a bike will lean, isn't then at that point , the tires, but rather the frame, exhaust, or sidestand, whichever you care to scape. Given these points, how can you make a decision which tire is better for knee dragging? Like knee dragging, balls to the wall days are over anyway.....I drive fast, but have learned not to drive stupid...I can, after 30 years on the bike, see there is a difference...even if I couldn't when I bought it at the age of 23 . Point I wish to make is....unless you push things to the limit..both tires must be ok, and if you have the need to push things to the limit, you may indeed find one tire does go furthur over in a corner, but which one was it? I'd rather not the only way to find out is to crash.
OK, you got me. Busted. I still don't have my frame back from the welders/powder-coaters to hang my pretty new wheels off of... so I wanted to show you all a pic and have you say, "Ohhh, pretty......". Please acept my apologies for the gratuitous pic posting and compliment fishing. :wink:

FWIW, I wanted to put the talk about tire prices in perspective. Doesn't matter if they're $140 each - they're still pretty durn cheap compared to things reasonable people might do to their Nort'ns. (Especially so when compared to something like a MkIII hub and rear disk conversion. :shock: ) My vote is usually for the product at the sweet-spot in the price-performance curve. However, if whatever-it-is is relatively inexpensive, I go for the better/best.

And, yep, you're right - frame and suspension are more important than tires. Hence sending my frame out to be blueprinted and straightened, converting to MkIII vernier iso's and rear swingarm and adding an OldBritts headsteady. A nice set of shocks, rebuilt and modified forks and a steering damper round out the package, so I figure it *should* handle. (knock on wood)

Finally, I'm a safety whore. No silliness on roads where they allow people to drive them coffins around. My knee dragging will be reserved for the track.

Since digging in to this project last June, I've decided to try my hand at AHRMA racing and that's what the bike's being built for. No center stand, the Steve Maney exhaust is tucked up by my left knee and the rear-sets are pretty high off the ground. Ergo, the 110/80VR18 and 100/90VR18 Supervenom's.

Ummm... rain grooves... whoops.... nothing to add on that topic, sry. :oops:
you might want to think about the (here goes my plug) rod end setup for the front mount and headsteady that I make if you are going to race it. neither one requres welding and no more adjusting the front mount or side play in either mount. and what are you doing to tighten up the swingarm pin in the cradle. I also have collers to lock it in unless you are going to use the mk3 style cradle with cotters.

Thanks Bill. I might take you up on the rod end deal. I've already taken the plunge on a MkIII swingarm and engine cradle - so that's settled.

Unfortunately, the MkIII cradle presents its own problems. Its got no adjuster-slots for the tranny, so I've got to find another way to tension my belt drive primary. Hmmmmm???

First things first though, I'm itching to get my frame back in-house. I'm going insane drilling bolts for safety-wire and want to do something that feels more like I'm making *progress*.

Ohhh... darn, now I've *really* hijacked the thread. :roll:

Take care,
if you can, take the cradle to a machine shop along with the old one and have them mill the top slots in it.

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