Tyre Size

[Markc73]

Just wondering if anyone can help me, I need to put some new tyres on my 54 plate RAV 4 2.0 Diesel. I have 16" rims and the standard recommended size is 215/70 16. I'm looing at the BF Goodrich AT tyres but everyone seems to be out of stock however I can get the same brand in 225/70 16. Would these fit straight on to the car or would I have to change anything?

I'm looking at the BF ones as I do a bit of gentle off road on a couple of farms and these have good reviews.

[Heidfirst]

your speedo would read about 2% lower than currently.

[Bouncerbeater]

The tyre on my stock alloys are 235/60/16 this is the other recommended size in my handbook. I've gone for larger rims on mine so couldn't comment re handling etc.

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[FROSTYBALLS]

Using a tyre size calculator your speedo with its current calibration, will under-read (show a speed lower than you're actually travelling) which is illegal - see http://www.autopartuk.com/tyre-calculator

Would need to get speedo recalibrated.

[Heidfirst]

Hi speedo currently probably over reads by ~7%, if so reading 2% less would still be legal.

[Markc73]

Never thought of the speedo issue but still wondering if the tyres would fit!

[Kommander]

Hi Guys. I have just bought a 2003 RAV4.2 NRG 3 door, without any handbook included, and was browsing to get advice on best tow bar choice (which seems to be some type of detachable plus Toyota plug in wiring harness). Anyway, one of the strings mentioned the effect of tyre size apparently choice between 215/70 R16 or 235/60 R16. So I had to check my tyre size physically to find they were actually 225/75 R16. This suggests my speedo should read either 5% slow, or 7.3% slow depending on which is the stock size for my model. This is assuming my speedo is accurate in the first place. From comments made this might well be illegal. Any comments?

[FROSTYBALLS]

The UK regulations as regards speedometers is as follows:

As with the UNECE regulation and the EC Directives, in the UK the speedometer must never show an indicated speed less than the actual speed. However it differs slightly from them in specifying that for all actual speeds between 25 mph and 70 mph (or the vehicles' maximum speed if it is lower than this), the indicated speed must not exceed 110% of the actual speed, plus 6.25 mph.

For example, if the vehicle is actually travelling at 50 mph, the speedometer must not show more than 61.25 mph or less than 50 mph.

[Kommander]

Thanks a lot Mike, that is VERY interesting. The tyres on the road wheels all show a good bit of wear too. I wonder if the insurance type warranty I am waiting to receive would cover me for a full set of tyres. Probably not worth the legal fees involved in trying to get compensation for sale of an un-roadworthy car from the dealer. Time to sleep on it at the moment; bad news but better to know about it.

[pmb]

11 hours ago, Kommander said:

Hi Guys. I have just bought a 2003 RAV4.2 NRG 3 door, without any handbook included, and was browsing to get advice on best tow bar choice (which seems to be some type of detachable plus Toyota plug in wiring harness). Anyway, one of the strings mentioned the effect of tyre size apparently choice between 215/70 R16 or 235/60 R16. So I had to check my tyre size physically to find they were actually 225/75 R16.

The NRG was fitted with 235/60x16 tyres.(same as my model) Some towbars can foul on the door opening. I have a detachable one on mine.Fitting instructions are on the toyota-tech.eu website if you are interested.

[Kommander]

Cheers Paul, I am interested in fitting instructions and will have a look at that link. I have since checked my spare and it is the 235/60x16 option. FYI I phoned the seller this morning to complain about apparent illegality of vehicle and gave him until tomorrow Monday to investigate and come up with a response/offer.

[Heidfirst]

16 hours ago, Kommander said:

Hi Guys. I have just bought a 2003 RAV4.2 NRG 3 door, without any handbook included, and was browsing to get advice on best tow bar choice (which seems to be some type of detachable plus Toyota plug in wiring harness). Anyway, one of the strings mentioned the effect of tyre size apparently choice between 215/70 R16 or 235/60 R16. So I had to check my tyre size physically to find they were actually 225/75 R16. This suggests my speedo should read either 5% slow, or 7.3% slow depending on which is the stock size for my model. This is assuming my speedo is accurate in the first place. From comments made this might well be illegal. Any comments?

your speedo probably over read on standard spec. tyres by ~6-7%. (so indicated 60mph a true 56 & with 235/75 at same speed would indicate 65). Going by what Frosty quoted that would be legal (could indicate up to~68 legally [56*1.1+6.25]).

Certainly an 8% differential in circumference is larger  than would normally be recommended.

[Kommander]

Heidfirst, thanks for your input. I accept what you say could be true factually, hard to tell without some sort of calibration test.

Problem is, in the event of a speeding offence, or worse, a road traffic accident investigation, if a vehicle's tyres are noted to be outwith the manufacturer's specification for that model, the MOT inspectors and insurers are not likely to be sympathetic, and the cops can justify their time spent.  Chances are that, if left alone, nobody would notice, but checking tyre size is also supposed to be part of the MOT test, and funnily enough the seller put this car through an early test on my (and maybe his) behalf.

Coincidentally, I once had a Ford Mondeo (transverse engine/front wheel drive) which, unnoticed by me, had front tyres each with a different profile height. At one point on braking, the offside front disc separated from the hub, and I had to get a tow home. I struggled to figure whether the disparity between the tyres could have caused some kind of stress, but considered that the differential would have balanced that out.

[alan333]

28 minutes ago, Kommander said:

Heidfirst, thanks for your input. I accept what you say could be true factually, hard to tell without some sort of calibration test.

I find sat navs consistent, ie they usually read about 5% under what speedos say, and therefore I reckon they're about right.  Could you borrow one and watch what speeds it says while you drive?  Maybe it would help give you some peace of mind.

[Heidfirst]

Certainly if running non-oem size you should inform your insurer & they may vary your premium.

[Kommander]

15 hours ago, alan333 said:

I find sat navs consistent, ie they usually read about 5% under what speedos say, and therefore I reckon they're about right.  Could you borrow one and watch what speeds it says while you drive?  Maybe it would help give you some peace of mind.

Good idea. I have an old Navman but don't know if it reads out speed. I will investigate.

[Kommander]

5 hours ago, Heidfirst said:

Certainly if running non-oem size you should inform your insurer & they may vary your premium.

Sensible consideration, but non-oem was not my choice. My spare is 235/60 so the present intention is to get road wheels reshod with either good S/H or new tyres to match. For my purposes, I am probably better with the broader tyre anyway e.g. I occasionally launch and retrieve a small boat. But that might be academic. Will decide when I hear what the seller has to say to me shortly.

[Kommander]

Hi guys, thanks all for comments. For general information, I returned to dealer today, and negotiated the removal of 4 worn 225x75x16 tyres, and fitting of a set of new (budget) 4x4 tyres 235x60x16 to match the spare; to which I contributed 50% of the price. I swear on the way home I could tell the difference in all gear ratios, presumably about 7.5%, and the car drove much more smoothly. I would have liked higher rated tyres, but as I am not a boy racer, having retired well over 10 years ago and only do about 3,000 miles a year, I think that was a satisfactory conclusion to my new acquisition. Only myself to blame for any speeding now.

[Avalon]

Your calculators fail to allow for wear (op states well worn), sat-nav's need to allow for altitude to accurately measure speed but are not certified to do so and shouldn't be relied on. From the posts above if it's been passed as fit for the road by a test station then you're going to have to spend a reasonable amount of time/money to prove the speedo is not accurate beyond the realms of what is permitted and as the permissible % is only slightly lower than the worst case scenario then it's going to depend on wear. If it bothers you change tyres to what the manufacturer recommends.