Dan 2

iTrader: (2)

I'm just about to get new tyres (215/40/17) for my Classic...

Does it matter what load rating they should be , if so ...what should i be putting on my wheels????????

Thanks

Dan 2......

Dan 2

iTrader: (2)

Anyone.........

finnie

Should be 87 or higher if I remember correctly

Dan 2

iTrader: (2)

Cheers Finnie.....

richiewong

AFAIK old Toyo T1-S 215/14/17's were 83W, many run these with no problems.

Dan 2

iTrader: (2)

83 or 87 ........or does it really matter what rating these tyres should be.

ALi-B

iTrader: (1)

I'm running 83W in 215/40 at the moment with no problems.

However might be wise to go for at least 87W or higher on Good Year GSD3s, as there was a spate of sidewall failures on the 83Ws when fitted to later (but heavier) models.

ALi-B

iTrader: (1)

I'm interested myself, so I though I'd delv into a little maths.

A stock classic shape impreza kerb weight is 1235kg and fully loaded: gross 1750kg (1800kg for wagon)

Can either go for the fully loaded weights to calculate 50:50 on the weight distribution(as it assume passengers+luggage), or the kerbwieght biased 60:40 weight distribution front to rear (assume no luggage or passengers).

For gross weight it's simply 1750/4 = 437.5 +10% safety = 481kg

For kerbweight calculate the heaviest axle (front):
so 60% of 1235 = 741kg
for each wheel = 741/2 = 370.5kg + safety of 20% = 444.6kg (car is unloaded, so need a bigger safety margin.

So you have between 444.6kg to 481kg as an approximate load on each wheel

Now compare to the load rating of the tyres:

83 = 487kg max @ 130mph
87 = 545kg max@ 130mph

You'll note that the 83W tyre does conform to the maximum anticipated load of the car.

BUT (and it it's a big and very important BUT):

The tyre load is increased the faster the car travels.
ALL load ratings on ALL tyres are rated at 130mph...any speed above 130mph undetermined and questionable.

So based on that 83w, tyres are suitable. But fully laden OR travelling above 100mph for any period is a risk (especially if you do both) as you are running close to the tyre's rated load rating.

So if you never go above 100mph, then yes on an OLD shape impreza, 83w rated tyres is fine.

If you like to go faster, or lug you boot full of crap, or have a newer shape Impreza (new age has a kerbweight of 1475kg ). Then YOU MUST use 87W rated tyres.


And anyone who has a bug eye or newage impreza fitted with 83w tyres. I highly advise them NOT to travel for any long periods at speeds above 100mph and not to exceed 130mph.

I think that more than answers the question now

Dan 2

iTrader: (2)

Thanks m8.......

krazy

Um, I think you are a little mistaken there, load rating is usually maximum load at the maximum or indicated pressure at the indicated speed rating of the tyre.
So your calculation above would also have to factor this in, and since your probably not driving round at 42 psi or something similar, the max load of the 83w tyre at approx 36 psi would be about 415kg.

abc

Very interesting post, thanks. Goodyear give a 91Y XL rating for 215/45/17 (= MY05) F1 GSD3s.

Cheers.

ALi-B

iTrader: (1)

NO it is not it is 130mph regardless of speed rating - I have checked 3 seperate sources to confirm this as I was doubtful myself (google it yourself if you don't believe me).

Also you you need to factor in that you are supposed to increase cold tyres pressure with incrased anticipated load and speed above the car manufacturers reccomendations (I did have a formular, but have lost it). Not to ignore pressures naturally increase caused by heat, due to increased load and speed.

The above calculations are a rough worst case calculation, with a large degree of safety employed (as well as the tyre manufacturers own safety margin).



But it would explain why some owners of impreza running Good Year GSD3 83y tyres have suffered structural tyre failure.
Which may indicate that in certain exteme situations these tyres are at the limit of their rated capabilities. The calculations confirm this.

And as said by abc, they reccomend their "extra load" tyre (XL) which is 91w for current models.

Dan 2

iTrader: (2)

87 and above for a classic then..?????

Tone Loc

iTrader: (1)

Prodrive recommend 87 as a min (one of the reasons the P1 has 225/35 R19 rather than 215/35 R18 from memory).....

However i run 215/35 R18 at the moment, not had any probelms but my average speed must be 50 mph on the journey to work with only me in the car

Tony.

krazy

That make little sense thou... and I have looked into it before, even the tyre manufacturers seem to think it is load at speed rating at given pressure...

http://www.michelin.com.au/tyres/tyr...peedRating.asp

http://www.fulda.com/fulda_uk_en/tes...exes/index.jsp

Are you trying to suggest a tyre rated to 112 mph will be load tested at 130mph?

ALi-B

iTrader: (1)

Funny Fulda say this on another page:

http://www.fulda.com/fulda_uk_en/tes...tyre/index.jsp

quoted from text on website:
If Fulda are going to contradict themselves, I think I'm just going to give up trying argue that one

Jerry B

Check your owners manual and/or the plate on the inside of the drivers door pillar - it should state the correctly rated/sized tyres. Best to stick to that for insurance purposes I reckon. The '03 lists nothing lower than 87.

And please note that a couple of us saw some inner sidewall splitting problems on 83 rated Goodyear F1s on classics - nothing proven or scientific to back it up, but I didn't see any posts that listed problems on 87 rated or above where the information was available. Mine failed an MOT - the first I knew about it luckily. They looked very bad indeed. No problems on several sets of higher rated ones I've used since on the '03.
Other brands I couldn't comment on.

ps I often have a full boot, but rarely anything heavy, and rarely more than one passenger. The classic was standard except brakes and 17" bugeye rims.

Dan 2

iTrader: (2)

87 or higher then.......215/40/17

What about 215/45/17 on a classic ???????

ALi-B

iTrader: (1)

Seeing I never looked before (as I don't have the original wheel/tyres) The plate on my MY97 scoob does actually state to use a 87V (205/55/15) tyre.

Although my current tyres are 215/40/17 83W but they've had a faily easy life barring the odd full laden trip (passengers and luggage) to Plymouth and back at 80+mph, and not suffered a failure in 15Kmiles (yes they are due for replacing ). I suppose it's down to brand and how they are driven.



Oh, and based on my findings, I'm going for a 87 as a minimum