tyre sizes

[callum]

hello...the man of a million questions...
I was curious about tyres. Ours are fine tread wise but starting to look a bit old. I have seen a set that look considerably better, on bongo rims that are 215/70/15 and 195/80/15. Will these be any good for a 4wd van? My normal tyre comparison site isn't working!

[Bob]

These don't look like the right tyres to me.

Mazda fit 195/70x15 front and 215/65x15 rear, but many fit 215s all round. Me included.

Also of vital importance is the load ratings. Min 92 front and 96 rear.

[callum]

it does say that the load ratings are suitable yes. I did wonder whether they were a bit tall.

[Bob]

They are a bit bigger and the difference in rolling circumference is 1.6% as opposed to 1% with the Mazda spec tyres, or zero with the same size all round. I don't know if this is acceptable on a 4wd.

This will give slightly higher gearing and the speedo will read a little slower.

Bear in mind your insurers will want to know about the 'Modification' and do check the age of the tyres regardless of the amount of tread.

There will be DOT then a four digit number. This is the week and year of manufacture.

http://www.carbibles.com/tyre_size_calculators.html

[cmm303]

Remember the spare needs to be the same rolling circumference to avoid damaging the 4WD

[Bob]

Very good point.

215/65/15 - 96 start at under fifty quid so it might be worth looking at buying new.

[callum]

A quick check on my tyres shows that they they are all 102 rated and made in 2009, so nearly 7 years old. I've seen older tyres that look in better condition, they are Nankangs.

[teenmal]

A quick check on my tyres shows that they they are all 102 rated and made in 2009, so nearly 7 years old. I've seen older tyres that look in better condition, they are Nankangs.

As far as date is concerned you really need to know when the tyres were first put into service, a new tyre can sit on a suppliers shelf for many years.

[callum]

oh, from what i read, when it was made was also of fairly big importance, whether it was on the road or not.
Fact is, either way, they have clearly been on the van a while and are not looking fantastic. Although, had these other wheels and tyres not popped up, i probably wouldn't have looked too much into it.

[Simon Jones]

The fitting date (or when first used on the road) is pretty irrelevant really, it's the date of manufacture and the conditions that they have been stored/used that determines the lifespan of the tyres. There are plenty of Bongo spare wheels knocking around that may never have been used on the road, but after 20 years the rubber will have started to deteriorate to the point where the sidewalls are likely to have cracked any may fail under load.

There doesn't seem to be any consistent advise from tyre manufacturers but 10 years seems to be the recommended lifespan.