Iam no tyre guru so Yet another tyre question

[Mikekitts81]

Been looking at scorpion xc tyres for my 660 build the front is easy one size only 21 inch ... the back iam undecided there's a 120/18 inch and a 140/18 inch so which is going to benefit me better the 120 or the 140 and why ????

[qcnr]

What aspect ratio are they, because this will affect the gearing of the bike and maybe clearance.
Ie a 120.80x18 will have a smaller diameter than a 140.80x18, as well as being narrower.

[Scott_rider]

A 140 tyre is going to be physically bigger than a 120 tyre so it depends if you've got enough space between the wheel and the swinging arm etc.
When I say bigger, I mean chunkier. Some tyres can be physically chunkier than the sizes suggest, so that's another consideration, for example the Mitas CO2...always looks to be far 'bigger' than it's dimensions suggest it is.

[garyboy]

I have found that wider rear tyres, (with knobblies, and low pressures) grip better `off-road`
but narrower rear tyres tend to handle better on-road (with 50/50 tyres, or road tyres) assuming they are near the oem size.

[halfpint]

on a 600 cc bike you will need 140 tyre , you will have to much power for 120 . you will find a low pressure and a large foot print on soft ground is better. a narrow tyre will cut in more and rip the ground up with 600 power ,on the road might be better to turn in but its still an off road tyre . just have a look what ktm are fitting on there bikes, 125 to 690

[chunky butt]

Tyres......always a compromise between grip and wear rate, be interesting to see the comments, and what you decide on...

[Mikekitts81]

What aspect ratio are they, because this will affect the gearing of the bike and maybe clearance.
Ie a 120.80x18 will have a smaller diameter than a 140.80x18, as well as being narrower.

The 120 is a 120/100/18 were the 140 is a 140/80/18 . I have also been looking at the desert tyres from motoz the tracitoner desert but they seem really expensive so I have been debating on the xc or the ac10 as I want them for road legal stuff but more off road oriented ... as I also have just bought a van so if need be my bikes can go in that but iam looking a a box trailor as well... the plan is to kit the van to sleep in but also take a bike if need be to green lanes etc ... but on race days etc rallys and stuff I can put bikes in trailor and sleep in van but at minute iam undecided on tyres

[halfpint]

put metz six day on the front not an ac10 on your asre on the road , good tyre for the rear but to hard on the front , 140/80 will be good just make sure you dont need f i m approved .. trye demon tweeks as they often have great deals

[Mikekitts81]

put metz six day on the front not an ac10 on your asre on the road , good tyre for the rear but to hard on the front , 140/80 will be good just make sure you dont need f i m approved .. trye demon tweeks as they often have great deals

Yea demon tweeks have good deals on thanks for that 75 for a pair .