Correct tyre size

Gundog · Guru

Correct tyre size

Dougwe · Chief one feather

Go with the stated size and get Light Truck tyres, Graham.

You might know that already.

Gundog · Guru

Only problem is the 225 75R15 has a very limited range to choose from I'm not happy with the current ones, but 2 different tyre mobs are suggesting either 225 70R15 or 235 75R15 which have a better range of choice. But looking on charts they suggest I would require 6 1/2 jj rims, am I being lead up the garden path.

Tony Bev · Guru

Not really sure, if they have to place the tyre load rating on the compliance plate

But...

I do know that different manufactures, have different load rating, for the same size tyre

As Doug has already said, light truck tyres, usually have a higher load rating, than passenger tyres of the same size

Opps

Edit to say that OP, posted while I was typing

If you google your tyre size, you should be able to find out, the load rating of most of the tyre manufactures, of that size

If you know the total loaded weight of your caravan, divided by the number of tyres, then that is the minimum tyre load rating you should get

-- Edited by Tony Bev on Monday 24th of February 2020 02:43:59 PM

Peter_n_Margaret · Guru

The load rating of the tyre MUST exceed the maximum legal load on the axle(s) and by at least 20% if it is a dual axle and not load sharing.
Personally I prefer a good margin when it comes to tyre load ratings.
Cheers,
Peter

Craig1 · Guru

The 225 is the width. 70 or 75 is the height( by means of an aspect formula ), so 70 is a lower height between rim and ground, or top of rim and top of tyre. 235 option is a bit wider, so you would need to check if that is ok for 6jj rim. Just googled one site which suggests that existing tyres are possibly too wide for rims

-- Edited by Craig1 on Monday 24th of February 2020 04:24:28 PM

Gundog · Guru

The load index is not the issue, it's choice of HT/LT is very limited, the majority have an AT tread pattern. Therefore the 2 major tyre retailers that suggested stepping up to a 235 75R15, are offering the wrong tyre for a 6JJ rim, if I did go with the suggested tyre and I had an accident because of the tyre say rolling off the rim, could they be held accountable for the incorrect advice. To get the best information I have checked a few web sites for the correct tyre for the 6JJ rim even there is conflicting information, 1 suggesting that 215 is the maximum size, even contacting Jayco results in whats on the compliance is correct.

yobarr · Guru

Gundog wrote:
On my Jayco's compliance plate, it states the wheel size is 6jj x 15 and the tyre size is 225 75R15, there is no load index stated.

Whilst I don't profess to be any sort of an expert on tyres,I was told waaaay back that 205 is the biggest tyre that should be fitted to a 6" rim? Cheers

Possum3 · Guru

Graham, Have a yarn to Colin Young Automotive Engineer (specialist in caravans) at Caravan Council of Australia. Read Technical Articles www.caravancouncil.com.au/technical-articles
CARAVAN COUNCIL OF AUSTRALIA
3 Margaret Street
Parkdale VIC 3195
T: 0409 865 399
F: 03 9587 1828

caravancouncil@optusnet.com.au

Greg 1 · Guru

The maximum width you can legally fit on a 6"x15 rim is 205. For a 225 tyre 7" is required and for 235 you need an 8" rim.

Peter_n_Margaret · Guru

Changing rims is not a complicated or expensive task.
My preference is to keep the trailer and tug wheels and tyres 100% interchangeable.
Cheers,
Peter

bobsa · Senior Member

Are the rims 6JJ ?
if so 195 x 15 LT is the size for that rim same as Toyota Hiace van and others
heap of tyres this size
bob

yobarr · Guru

bobsa wrote:
Are the rims 6JJ ?
if so 195 x 15 LT is the size for that rim same as Toyota Hiace van and others
heap of tyres this size
bob

The rims can take up to 205,but,as you say,there are many 195x15 LT tyres that may suit.Bridgestone has several to choose from.Cheers

Gundog · Guru

Remember the compliance plate states 225 75R15, if you change the the tyre to a smaller one, how could that effect a road side inspection, is it unroadworthy, therefore could that be an issue with your insurance.

bobsa · Senior Member

www.tyresizecalculator.com/tyre-wheel-calculators/tyre-size-for-rim-size-width-calculator

6jj or 8jj surely Jayco would get it right or someone has got it wrong
check the link for rim size to tyres

unroadworthy and insurance comes to mind

bob

Craig1 · Guru

Graham, usually somewhere on your rim the size will be stamped, maybe check that as well. If the 225 is fitted to 6jj is will look pretty baggy

Gundog · Guru

Now you have me wondering if I have miss read 8 as a 6, if not has the plate been stamped incorrectly will check that tomorrow.

Gundog · Guru

No I was correct it is 6JJ & 225 75R15, couldn't be bothered ripping a wheel off to check it, I have sent an email to Jayco questioning the validity of the compliance plate.

Cupie · Guru

If you don't get satisfaction from Jayco, check a similar van's compliance plate at a dealer.

My old 9/99 build Westport plate says ....

Rim Size Profile 6JJX14 .. Tyre Size 185R14 ...

Also says Tyre Press Cold 200(20kpa)!!!! ... Far too low IMHO. I have never run that low. I run 350(35kpa). No increase in temp at that setting.

Edit .. My tyre pressure calculator recommends 470 (47kpa) http://www.gnschassis.com.au/tyre-pressure-calculator/

Since new, I have always used Goodyear 185R14C Cargo G26 8ply. They have a HT tread & I don't do dirt or travel over 90Km/Hr.

Why Goodyear ? .. That's what was on it from new & I only replace on age, not wear.

Always about 50% of very evenly worn tread left when I turf them.

Current ones are approaching 6YO & will go before next trip west. They will be my 4th set including the original ones, averaging >70,000km each set.

The only problem that I had was the orig spare that sat on the back under cover & was foolishly put on in an emergency & forgotten. The tread lifted after about 1000km. It was around 15 years old at the time!!!!

I now replace the spare along with the others. $100 of safety expenditure.

ps. Mine is a 21'6" Jayco Westport dual axle rated ATM 2334

-- Edited by Cupie on Friday 28th of February 2020 10:16:10 AM

Gundog · Guru

I emailed Jayco mid week about the incorrect information about the tyres and rims, as I have posted the rims specified as 6JJ and the tyres are 225 75R15, which according to many tyre retailers and online information say for that rim it should be a 195 x 15 and 205 x 15 is borderline. Whilst having new tyres fitted today, I confirmed the rims are actually 7JJ and the 225's are about the maximum for them. Monday will be confrontation day with Jayco, I wonder what other information on the compliance plate could be wrong, or in fact if the wrong plate was fitted to the van. I will be demanding a replacement compliance plate be supplied with the correct information. Because I consider that authorities could put the van off the road or insurance companies could use that information to deny a claim, if I was involved in an accident.

Gundog · Guru

Jayco think they have won suggesting that a 225 x 15 tyre is suitable for a 6JJ Rim, but this is not end in my view more to come.

swamp · Senior Member

HI
225 tyre minimum width rim is 6 inch . Personnel [tyre shop] opinions get in the way . Been thru this time and time again . Almost all my cars and vans run either 225or 235 tyres . 3cars 1 trailer 1 van
Minimum rim for 235 75 15 is 61/2 inch fitted factory to a Ford Ranger

Refer tire and rim association USA
Refer tyre manfacturers

Tyre profile might influence tyre makes recommendation
but 225 fitted to 6 inch rim done b4 and legal
235 fitted to 61/2 and 7 inch rim and legal

yobarr · Guru

Gundog wrote:
Remember the compliance plate states 225 75R15, if you change the the tyre to a smaller one, how could that effect a road side inspection, is it unroadworthy, therefore could that be an issue with your insurance.

Tyre chart....facts. Cheers

-- Edited by yobarr on Monday 16th of March 2020 10:01:50 AM

swamp · Senior Member

HI
Yobar
That list is not consistent with TRA Tire Rim Association

Tire aspect ratio does have an influence on rim fitttment but for 70--75 series aspect ratio rim sizing is as I mentioned earlier

225 70-75 min rim 6inch
235 70-75 min rim 6.5 inch

Going to lower profile tends to widen rim requirements for some sizes
235 60 15 some brands require 6.5 inch some brands require 7 inch