just replaced a worn out set of 2.1 fire xc pros with with a pair 2.1 IRC mythos xc.They look like they are smaller dont fit on the´xm317s so well making the wheels wobbly.I did pump them up pretty high but not thát high.Should I try running them lower pressure to make thicker and fit on rims better or are they just shit tyres like used Conti vapor which also made my rear wheel wobble as if it was massivley buckled.Put on the old fire xc everything fine.

Unless you’ve been unlucky and got a duff tyre it just sounds like the tyre bead has not seated properly.

Try and refit it and if need be pump them up until you hear it ‘ping’ into place (should go by the time you hit 50-60psi then let air out to your required psi). You should be able to visually see where the tyre has not seated.

What he said.

Soapy water on bead helps seat properly.

thanks I will try that.Think I am going to put my old fire xc pro up front again until I get a replacement(maybe a Rampage SC )and the keep the Mythos xc’s for burning up on hot tarmac on the rear in the summer.Saving money on tires isn’t really worthwhile got the pair of Mythos xc’S from Hibike for under 30 Euros they really just for hardpack and not very high volume compared Panaracer’s 2.1s.