The Blockley Tyre Company Technical Articles

Why are tyres dual marked ?

Have you ever been confused or wondered why tyres are often marked with multiple sizes on them such as 500/600x19? Or you order a 550x18 tyre and what arrives is marked up 525/550x18 or 550/600x18 on the sidewall?

Tips on fitting your wire wheels

Valve stem diameters and uses

For most "old car" applications the valve stem hole in the wheel rims come in 3 sizes, which are nominally:

Tyre size Equivalents

Some useful approximations for tyre sizing.

Remember that Radial tyres are on the whole 80% the diameter of the cross ply, so very often a tyre that is the equivalent could be smallon diameter, but to get the diameter then it's a "fatter" tyre. We can always try and advise if you are stuck as to which Blockley radial tyre size you require! For example cars maufacturers that specified 6.40x15 in period would give differing radial options of 165R15 and 185R15. . . . But all teh same the list below should prove helpful.

Why are metal valve caps safer?

Blockley include metal valve caps with our inner tubes as standard. Why do we do this?

Blockley Radial Sidewall labeling

Blockley Radial Sidewall labelling

Why high speed rating?

We are often asked why all Blockley radial tyres have such high speed ratings - typically T (118mph / 190kph) on the smallest sizes, H (130mph / 210kph), V (149mph / 240kph) or W (168mph / 270kph), where the tyre sizes are typically fitted to vehicles with significantly lower achievable speeds.