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Hi All,

Sorry, there may well be information on this in the specific forums, but I haven't got access yet to check.

My 2012 Caddy Maxi Life 4motion currently has stock 205/55/R16 tyres on 16" factory alloys. I'm about to change these for Nokian Weatherproof tyres as I drive in do a lot of winter mountaineering, but don't want to have to keep changing tyres (don't have the space for spare wheels atm).

I'm slightly tempted to go up a tyre ration to 205/60/R16 to gain an extra 1cm of ground clearance (from ~15 to ~16 cm), but I'm thinking the loss of acceleration and I assume handling (more side-wall to flex) won't be worth it. Anyone done this and have any experiences to share?

I wen up both width and height wise on my old T4 syncro, but this had very aggressive (don't know if that' the right word) gear ratios, so I didn't notice the loss in acceleration much, and with a low geared 5th gear it improved the cruising speed, but it also drove like a boat.

Not had any experience on a caddy but on other vehicles, swapping tyre sizes by such a relatively small amount shouldn't make too much of a difference. I assume it's not a track bias vehicle with you mountaineering so the extra flex in the sidewall shouldn't really be noticeable.

Hope this helps.


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Hi Lanky, thanks for the response, probably being a bit dim, but what do you mean 'not a track bias vehicle'?

Hmm..

Rather than guessing you can test out your ideas with a free online comparison tool - http://www.kouki.co.uk/utilities/visual ... calculator which will allow you to input different rim and tyre size/profile combinations to find out if they have the same effective rolling radius.

Inherently as you increase the effective rolling radius, you will also slightly increase ground clearance but this will also affect the accuracy of your speedometer/trip-meter. If the speedometer is too inaccurate, it may make the vehicle technically un-roadworthy.

On my maxi 4motion, the rear differential is the point with the most limited ground clearance, where the un-laden clearance is only 16.5 cm with 205/55/16 Goodyear Vector 4 season tyres fitted. Interestingly if you had a 2WD maxi with a straight tube rear axle you would have at least 5cm extra clearance - so do you really need 4WD or just ground clearance?.

If you are really only looking for 1cm extra ground clearance, then you will probably get that when running brand new tyres with full tread depth, or indeed just increasing your tyre pressures temporarily.


SnoWhite

My 2wd on 205/65/16 Yokohama Geolandars. Ride well, no noticible problems with gearing and mine is only a 1.6tdi, i wouldnt hesitate to fit them again. My speedo under read by 6% and these are 6% bigger so is now dead on, if you have issues it can be adjusted on VCDS.

Thanks for the replys.

@SnoWhite:

I'm aware of the changes in tyre size equaling circumference and ride height change, hence the request regarding people's experiences. I already own the 4motion, and specifically got one as I often drive on muddy fields or snow, and hence that was my priority. The ride height is secondary in my off-road driving requirements, but is useful for rutted tracks etc. which I also often find myself driving down. I haven't measured the ground clearance myself as I know that new tyres is going to improve it anyway, but was just going off the stats I've read online. I don't think the loading of the van can realistically affect the ride height as it's leaf-sprung above the solid axle.

I'm not sure if it's worth me thinking about this really, but just thought buying tyres is the time at which I could try and maximise this, without any specific requirements, but don't relaly want to reduce the road handling in terms of cornering.

@Audisport:

That's good to know that you don't have any issues running 205/65/16, that makes me think maybe I should go for it (or maybe match your size). Do you ever get issues with catching the inner arches on full lock?

My speedo also under reads currently (by about 7%) so I could easily increase size and stay legal from that point of view. However, if the tyres I googled based on your recommendation were correct, those aren't appropriate for my caddy as the speed rating is too low (H rather than V), and I couldn't find any AT tyres which would fit my caddy with the correct specs, hence moving to all-weather tyres as the ones selected do have some tread for mud, and will perform much better on snow/in the wet.

Anyone else run larger tyres and have an opinion on the difference in handling/cornering? Or know if the extra strain on the haldex could cause any issues?

Thanks,

Robin

Your caddy does more than 130mph the H rated tyres are good for?

No catching or anything, I did plenty of research and the reason I bought those tyres is Seikel went to the effort to get the 205/65 Geolandars TUV approved for Caddys, (I've just looked and it looks like they have obtained approval for that general size as I think the geolandars have been discontinued) . If you want more ground clearence look at their site, they offer lift kits, mind you only tyres help with the low diff.

Regarding haldex I wouldn't worry I've got a Golf 2.8 4motion and that rear diff has taken plenty of abuse. The thing with haldex is that it is rarely engaged so I can't see the bigger tyres being an issue (again seikel have vw approval as far as warranties go I believe for the lift kit and the tyre size I mentioned)

I'm not sure about the latest gen haldex but I found the trickiest thing with Haldex cars is getting the dealer to acknowledge it needs the oil changing, they have always been reluctant to do it for some reason in my experience.

Thanks Audisport, that's really helpful! However it appears from their information that they only approve those tyres sizes if you've had the lift kit fitted (may have been different when you got your tyres, but that seems to be what they're saying now). If I decide to go for some larger tyres (just found the ones I wanted don't have the load rating in the larger size anyway I don't think), I think I'll just contact my insurer and warranty supplier to check they're OK with it.

Now I'm tempted by the aluminium undertray...

I've fitted the biggest diameter tyres I was able to find on my Caddy and I'd say there's not much to worry about unless your diameter exceeds 671mm (mine is 668mm). I have these tyres fitted to 15" rims (as opposed to the 17" the car comes with), and there are no acceleration or gearing issues. Of course there is more "lean" around corners going from 17" to 15" but nothing critical.

You can calculate your wheel diameter here: http://www.wheel-size.com/calc/



VW 15" SIMA alloys (sprayed matte black) with 205/70R15 Goodyear Wrangler AT/SA+

Bloody hell they look like all terrain tyres


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Great looking caddy there anoneamus!

I ended up going for 205/60 R16 (92H which is just higher than axle max weight and much higher than max speed). The 205/65 R16 would have made it 673 mm diameter, so slightly too large by your reckoning (where did you get this figure from?), although only saw this after ordering them a few mins ago. I think it'll be a good compromise in clearance/closer to the money speedo and motorway cruising vs handling/acceleration.

Can the speedo not be adjusted in vcds?

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Robin UK wrote:Great looking caddy there anoneamus!

I ended up going for 205/60 R16 (92H which is just higher than axle max weight and much higher than max speed). The 205/65 R16 would have made it 673 mm diameter, so slightly too large by your reckoning (where did you get this figure from?), although only saw this after ordering them a few mins ago. I think it'll be a good compromise in clearance/closer to the money speedo and motorway cruising vs handling/acceleration.

Thanks, it's the Cross Caddy. I spent a lot of time trying to figure this out, putting together largest sizes I've seen posted on here and elsewhere. 671mm is the biggest I've seen anywhere. You may have been able to get away with 673mm, but it would have been very close. The point you need to watch is the rear arch (which is where the tyre comes closest). With my tyre there's about a 10mm or less gap, which is fine on the road, but if any mud sticks to the tyre it begins to touch (the mud, not the tyre!).

Chris017 wrote:Bloody hell they look like all terrain tyres

That's exactly what they are! This is the Cross Caddy, so it needed them!

I wonder if you can get the Caddy Cross trim OEM. The arch protectors at least might be a good idea on my van if they fit. Also, do the under carriage guards extend further than the bumpers? Are they plastic or metal? I was tempted by the aluminium engine tray/protector from the site linked above, but they're a bit more than I want to spend just now.