What is the biggest 18" dirt-track tyre you can get?

[John Orchard]

Too the Dirt-track guru's on the site, is it possible to get a 5.00x18 trail (non claw pattern) tyre to use on Dirt-track?

All the guys at Broadford seem to be running the 4.00x18 Micheling trials tyre but I feel that 250 2-strokes & 450 4-strokes could benefit from a wider rear tyre for that all important holeshot.

[SON]

Bridgestone and a few of the cheapies made 4.50s they were popular with some on Sidecars.
For Dirttrack the Michelin is king

[tony27]

Trials tyres are limited to 4.00 by the fim & have been for years, if you want wider then it's likely to be a cheap asian tyre that won't bite as well as the trials tyre

[John Orchard]

I've found a 4.50x18 Cheng Shin, we'll see how it goes.

[micks]

have a read in the MOMS in modern dt there is a rule about max tyre size, that maybe the reason why they run 4.00

[firko]

I had a bit of a look at what the fast modern guys were running at the last Nepean practice day and those that weren't running Maxxis flat track tyres were running either 400 Michelin or Mitas 2 ply trials tyres. Those wide trials pattern dual purpose "trials universal' tyres are rubbish on DT. If a 2 ply trials tyre can handle a 60hp modern it'll handle most other situations. You may get your holeshot with the 4:50 Chen Shin but this is dirt track racing not drag racing, you have to get through the corners. The correct tyre choice is the most important decision you'll make when setting up a dirt tracker.
Below: My newly completed flat tracker showing its 400 Mitas trials tyre on the rear and Dunlop K180 dirt track tyre on the front. 
                                                                    

[JohnnyO]

A 4.00 Michelin will get better traction than a 4.50 Cheng Shin. There's a reason they all use Michelins. A 5.00 will be too big, you want the thing to get thru corners, it'll push the front if the back's not sliding.

[Graeme M]

Yep, what JohnnyO and Firko said

I have ridden back to back a 4.00 Michy and a 4.25 or something Cheng Shin trail tyre and the difference was scary. The Cheng Shin wandered everywhere and was actually dangerous in the transition from grip to slip. I know guys can pretty much ride on any old tyre, but for my decidedly average skill level I need all the help I can get. Get a proper 2-ply trials tyre from Michelin, Dunlop or Mitas, you'll be glad you did.

[firko]

I use an old Dunlop K120 trials tyre on my Maico (mainly because it's already mounted on a Maico rear wheel) which has been on there since the late 80's. I've got Michelin and Mitas on my other bikes but I like the Dunlop as well. I've Googled and couldn't find the K120 listed any more but found the Dunlop D803 trials tyre which I presume replaced the K120. They're pretty cheap compared to the IRC and Michelin and on par with the Mitas. Has anyone tried them on dirt track?

[John Orchard]

Is that Mitas only a 4.00"  it looks bigger in the pic?

[tony27]

The D803 is the replacement for the D801 which I used to use on my trials bikes in the 90s, supplies dried up over here after the Kobe earthquake & I don't recall the importer bothering to bring them in again. I think by the time that dunlop was producing trials tyres again the IRC tyres had improved enough to take over their market share
No idea when the K120 first came out or was phased out

[firko]

Is that Mitas only a 4.00"  it looks bigger in the pic?

Yep, a 400

[steve234]

Goldentyre have a trials tyre that has every third tread row missing. They should hook up in loose deco like a paddle tyre.

[tony27]

Have actually seen 1 of those tyres in the last couple of weeks, thought they'd be ok for rocky trails or tree roots but would be seriously illegal for use in trials, would probably be fine for dirt track seeing as it's only the centre rows that are removed   
Quite a bit cheaper than a Michelin or IRC trials tyre
http://goldentyre.co.nz/cart/index.php?route=product/product&product_id=63

[Curly3]

Dirttrack is about finding the fine line between too much & too little traction. One of those missing row tyres might be okay on a big bore MXer. Not sure about everything else.
Fraz & TH would've loved em.