GS425 tyre size.. what have you managed to fit?

[TDIPower]

Im street tracking my GS425 and have been looking at the Dunlop K180 tyres the thing is the smallest ive found are 130/80 18" while using a ruler to check the distance I think I could squeeze them in front and rear, with a possible mod to the torque arm for the rear break.

So what have you lot managed to get.

Cheers Pete

Pic of the GS at the moment.

 

[Nessism]

Selecting tires is not about "squeeze(ing) them in front and rear", the important thing is to match the tire width to the width of the wheel.

For example, with a common 1.85" front wheel the most appropriate tire size is 100. For the rear, a 110 can be used with a 1.85" rear, or a 120 with a 2.15", and 130 with 2.50" wheel. If you go wider than these sizes the tire will be excessively curved which can effect handling. Of course some people ignore these details but you shouldn't.

 

[GregT]

Currently running a 140/70 on an 18 x 4.00 rim in a standard arm.
The torque arm is the stocker - but onto a caliper carrier.
Too much work realistically for a street bike - and the quicker riders on this tell me they can feel frame windup on fast sweepers.
For this level of grip I should brace the frame & arm.

Greg T

 

[Steve]

Currently running a 140/70 on an 18 x 4.00 rim in a standard arm.

That's all well and good, because you have a 4.00 rim in there. The problem is that VERY FEW 425s are swinging a 4.00 rim.

If you have the standard rim, your best bet will be a stock size tire, which is probably a 120.

In the case of motorcycle tires, wider is not necessarily better, unless you have the proper wheel to support the tire.
Even then, the change in profile can affect the way a tire rolls into a turn. Many of the guys here have stuffed a 110 on the front for "better traction" only to take it off and put a 100 back on because it feels better, more neutral in the curves, and still PLENTY of grip. Newer tire compounds are vastly better than what was available back when these bikes rolled off the production lines.

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[GregT]

I quite agree Steve, but when upsizing - or asking for info on doing it, there are two limiting factors.
1 what sizes fit your rims correctly.
and
2 what tyre size can be accomodated in the standard arm.

I think I've answered the second part and you've answered the first.

Greg T

 

[Steve]

I think I've answered the second part and you've answered the first.

Quite true, quite true. Do you think that, between the two of us, we might have answered his question to his satisfaction? :-k

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[TDIPower]

well folks i got sucked into my own world... ive got my self back into this one and In the end I fitted 4.00 on the rear and 3.5 on the front. this is the bike finaly back on the road

Pete