Tyre size increase.

[danielj]

Any thoughts on what percentage increase in tyre size / rolling diameter should be ok without any major affects on steering etc?
The question is not about my T2 but about my Mazda pickup. Stock tyres were 205 / 16 and I increased to 245 / 70 / 16 which gives me about 8% increase in rolling diametre. Thinking of going up to 245 / 75 / 16 and putting a set of Kumho KL71's on. Would give me about 11% increase over stock. Had been planning to go down to 15's to keep the rolling diameter closer to stock with bigger tyres but the 15 inch rims I have been promised won't be available for a while. Clearance for 245 / 75 / 16 does not seem to be a problem as there seems to be plenty of space under the wheel arches.

 

[lacroupade]

Any thoughts on what percentage increase in tyre size / rolling diameter should be ok without any major affects on steering etc?
The question is not about my T2 but about my Mazda pickup. Stock tyres were 205 / 16 and I increased to 245 / 70 / 16 which gives me about 8% increase in rolling diametre. Thinking of going up to 245 / 75 / 16 and putting a set of Kumho KL71's on. Would give me about 11% increase over stock. Had been planning to go down to 15's to keep the rolling diameter closer to stock with bigger tyres but the 15 inch rims I have been promised won't be available for a while. Clearance for 245 / 75 / 16 does not seem to be a problem as there seems to be plenty of space under the wheel arches.

doesn't seem to have affected people who've done it half as much as jacking their suspension has - but i think one consideration might be the alleged price differential and/or tyre choice between 15" and 16" wheels, in favour of the former....

 

[danielj]

doesn't seem to have affected people who've done it half as much as jacking their suspension has - but i think one consideration might be the alleged price differential and/or tyre choice between 15" and 16" wheels, in favour of the former....

The price of 15's is a bit cheaper and choice does seem a bit better. If I had my hands on the free 15 inch rims I have been promised I would probably go with 15's but I'm getting impatient waiting for them and also stuck off road so the idea of new tyres is niggling me again. So far can't say I have noticed any problems with the increased tyre size I'm using. Thought I would get some thoughts from others before any possible further increase.

 

[Terranosaurus]

I've got 32/9.5/15 on mine from a std 235/65/16 which is a noticeable jump and means my speedo is now about spot on where it was well out before. On the very steepest of motorway hills I have to shift down to 4th to maintain 70 (ish!!!) mph but the rest fo the time no problem. But that is on big muds with a far from aerodynamic roof rack too - would probably be ok without either.

Offroad you have a bit more chance of breaking a shaft but minimal if you don't go mad.

 

[danielj]

I've got 32/9.5/15 on mine from a std 235/65/16 which is a noticeable jump and means my speedo is now about spot on where it was well out before. On the very steepest of motorway hills I have to shift down to 4th to maintain 70 (ish!!!) mph but the rest fo the time no problem. But that is on big muds with a far from aerodynamic roof rack too - would probably be ok without either.

Offroad you have a bit more chance of breaking a shaft but minimal if you don't go mad.

Most of my driving is on-road but need to get the pickup across mud tracks, fields, rocks etc. doing some work most weekends. I don't go mad too often but have been known to try some stupid things with the truck just to see if they can be done. I'm sure you know how that goes:naughty:naughty

 

[extreme-4x4]

mine was ok on 35 12.5 16
gearing wise was ok . wasnt slow

however breaking is reduced the more you go up , the steering joints dont like it.

actually bent a steering idler just by heavey breaking once

think mine worked out about 19% bigger than standard :thumbs

 

[PCshedman]

As documented elsewhere I have had a mixture of 235/75 x 15 and 215/80 x 15 on my Maverick. Now about to get all four the same. What are the advantages of both? Performance in snow is my main concern.

 

[lacroupade]

As documented elsewhere I have had a mixture of 235/75 x 15 and 215/80 x 15 on my Maverick. Now about to get all four the same. What are the advantages of both? Performance in snow is my main concern.

well your 215 is 20mm narrower than the 235 is all....but as I worked out in your other post, the sidewall sizes will be slightly different which is bad news when in 4WD.

 

[PCshedman]

Am making all four the same size. so should I go for all 235/75 or all 215/80 for best in snow?

 

[lacroupade]

Am making all four the same size. so should I go for all 235/75 or all 215/80 for best in snow?

well the OEM is 235 generally.

theres a school of thought that says skinnier tyres are better for ploughing through mud (so you can do stuff in a 2CV for example that you couldn't do in a normal car) but I would have thought you want a wider footprint for snow really?

But I don't think either are going to make that much difference TBH - you probably need proper winter tyres or a mud tyre with massive open tread, but they are crap for road use.....

 

[PCshedman]

In my hanbook for a 1994 model it says 215/80 is original size - so as there is no real difference I might as well get 215/80 the cheaper size?

 

[lacroupade]

In my hanbook for a 1994 model it says 215/80 is original size - so as there is no real difference I might as well get 215/80 the cheaper size?

forgot you had an older truck - I'm sure fitting bigger rubber wouldn't be a prob, but when budget is important its a no-brainer. :thumbs

 

[PCshedman]

As usual, thanks mate!

 

[elty001]

my 1996 mk 1 terrano had 215/75 15's as standard(now on 31/1050 15's)
my 1997 mk 2 terrano has 235/75 15's as standard.
ran my mk 1 on 235/75 15's kuhmo kl71 mt tyres for a while with no issues.
had to trim the bumper and lose the mud flaps when i went up to 31's but the wheels have a greater off set than standard rims.
get my tyres from this place
http://www.camskill.co.uk/products.php?plid=m26b0s95p0
have to get them fitted locally but i know a tyre fitter so get them done cheap.

 

[danielj]

well the OEM is 235 generally.

theres a school of thought that says skinnier tyres are better for ploughing through mud (so you can do stuff in a 2CV for example that you couldn't do in a normal car) but I would have thought you want a wider footprint for snow really?

But I don't think either are going to make that much difference TBH - you probably need proper winter tyres or a mud tyre with massive open tread, but they are crap for road use.....

Thanks for all the replies and thoughts on tyre sizes. On the subject of skinnier tyres my own experience with 205 / 16's was that the skinnier tyre did dig into the mud quicker. Problem I found though was that when there wasn't something solid under the mud they kept digging until nearly up to the axle. With a wider tyre they were slower to dig and didn't sink as much. A lot probably depends on the type of ground and whether digging is going to get you deeper in a hole or gain you some grip. On snow I would have thought the wider tyre would be better. But as has been said tread type is probably more important than tyre width. Happen to be using 245/70/16 Cooper Mud and Snow thread at the moment. Granted they are part worn but they don't get me far in the mud. Can be slippy sideways in the wet on tarmac at times. Didn't have any problems with them in the snow but didn't push them too hard.

 

[lacroupade]

Thanks for all the replies and thoughts on tyre sizes. On the subject of skinnier tyres my own experience with 205 / 16's was that the skinnier tyre did dig into the mud quicker. Problem I found though was that when there wasn't something solid under the mud they kept digging until nearly up to the axle. With a wider tyre they were slower to dig and didn't sink as much. A lot probably depends on the type of ground and whether digging is going to get you deeper in a hole or gain you some grip. On snow I would have thought the wider tyre would be better. But as has been said tread type is probably more important than tyre width. Happen to be using 245/70/16 Cooper Mud and Snow thread at the moment. Granted they are part worn but they don't get me far in the mud. Can be slippy sideways in the wet on tarmac at times. Didn't have any problems with them in the snow but didn't push them too hard.

As we've found on one or two of our 'adventures', unless its a proper mud pattern, even if you don't sink, the tread fills with mud very quickly and the wheels just spin....

 

[danielj]

As we've found on one or two of our 'adventures', unless its a proper mud pattern, even if you don't sink, the tread fills with mud very quickly and the wheels just spin....

Unfortunately very true. The very reason some nice Kuhmo's on the Camskills site are looking so tempting.