13" wide 18" rim tyre problem

[carbuilder2002]

I have startedtolokfor newtyresfor the rearofmy car as the existing ones are getting towards the 2mm limit in parts, the existing ones are 345/35/18/Z.
I am told that this size is no longer manufactured has any one got ideas on the best option.
Ihave beenloking at 335/35/18 and 325/40/18 but not sure if they willbe okon the rims?

[carbuilder2002]

Sorry my space bar was acting up

[MagicRat]

Both Kumho and M&H make tires in this size. Both are mostly a race tire.... and are probably pretty soft, not long-wearing, and both would be a handful in the rain.

Otherwise, the 335 tires would probably be a good bet. Tires generally have some tolerance for the rim width that they will accept. Hopefully the 10 mm reduction in tire carcass width would fall within tolerances.

I would suggest have your tire retailer trial-fit one 335 tire on a rim, and then see how well it fits.

[curtis73]

Visit the tire manufacturer's website. They list acceptable rim widths for all of their tires. Check to see if the narrower tires will fit on your wheels.

[carbuilder2002]

Thanks already been on websites and the 335 are OK on 13" rims but I will lose about 10mm in rolling radius

[MagicRat]

Originally Posted by carbuilder2002

I will lose about 10mm in rolling radius

You shouldn't lose that much.

You will lose 10 mm in carcass width. But since this is a 35-series tire, where the tire sidewall height is 35% of the carcasss width, you will actually lose only 3.5 mm in radius.

[curtis73]

Agreed. The tire carcass stretches a bit and might change the diameter by 1-2mm, but certainly not 10mm.

Like Magic Rat said, the second number is a percentage of of the width on the sidewall. Going from 345/35 to 335/35 will reduce your radius by a small amount. You might be speaking of 10mm circumference. For every revolution of the 335 tire you might have travelled 10mm less than with the 345 tire (to late to do the actual math ) but on the grand scale, it means almost nothing.. in fact it means about 1%. So when you're speedo says 100kmh, you'll actually be travelling 99kmh. Since factory speedometers are notoriously off by as much as 5 kmh, worrying about 1 isn't worth losing any sleep.

[carbuilder2002]

seems I can only get 330/30/ZR18 here in the UK as neither 345/35 nor 335/35 are available.

[MagicRat]

Originally Posted by carbuilder2002

seems I can only get 330/30/ZR18 here in the UK as neither 345/35 nor 335/35 are available.

Get on the net and buy the 35-series tire from an overseas vendor and have them shipped to you. There are lots of them around.
Your local dealer or decent mechanic could install them for you.