Question - Tire Load Ratings

[JeepGeek]

I need to put new tires on my Jeep Commander. The OE size is 245/60R/18 105S Goodyear Fortera HL. This, as I am finding out, is not a real common size, so my choices are limited. The guys at Firestone are telling me that I could put on 245/60/R18 104S and that the load ratings really don't mean anything. Then, I talk to the guys at Goodyear and they tell me that the a Goodyear's 105 load rating may be the same as a Firestone or Michelin's 104 load rating - that there's no standard for this rating.

That statement by the guy at Goodyear really doesn't make any sense to me at all - if it didn't really mean anything, why would the manufacturer's bother to put it on the tires?
I don't really want to compromise safety by having the incorrect tires installed. I don't doubt that the 104 rated tires would be "OK", but I honestly think the 105 load rated tires would be better. The overall difference is only 55 pounds per tire (220 pouds for 4), but that may be the difference of having an issue, especially with a vehicle loaded to the hilt for a trip going down the highway at 75 MPH. There are a lot more options (Michelin) if I go with a 104 rating.

Can anyone offer any insight on this? I need some sound advice. Thanks.

 

[2oldtommy]

I suggest you go to the Tire rack website to get your information. From your comments, it seems like you have been given incorrect information. Tire rack also shows load ratings under "specs" for every tire they sell. FWIW--Oldtommy

 

[azjake]

Load rating is the one thing you don't want to mess with when replacing tires. And yes, there is a US standard for load rating (tirerack has it on their website).

 

[eljefino]

You would fail a maine state inspection if they found underrated tires, as compared to your door jamb or the "tire bible" book.

Are you sure you don't have a door jamb calling for 104 while your current 105 tires are over-rated?

If you go higher in sidewall, like a 65 series, you're very likely to increase load rating. Many tire manufacturers have charts.

I suspect (highly!!!) the guys at Firestone were trying to push a tire they had in stock, out the door. If your rareness of your tire is such an issue, buy them online already and skip those bozos, or at least deny them some profit.

The thing for which there is no uniform standard is treadwear, a goodyear 300 vs a firestone 350 might not mean anything. Supposedly a goodyear 600 is 2x as good as a goodyear 300 though.

 

[Ken2]

What is the actual max load capacity of the tires of the different designations as molded into the tire sidewall?

 

[Gene K]

As far as I know all Commanders came with 105 Load Index (2039 lb) Tires. Both the 17's and the 18's were 105's.

 

[JeepGeek]

Thanks for all of the info and advice.

I checked the doorjamb placard - definately 105.

I agree about the guys at the Firestone shop - just trying to get a sale. They were trying to sell me the Destination LEs with the 104 rating which they said several times were in stock. I inquired about the Destination STs, which have the 105 rating (they would have to order). They said the STs weren't really for Jeeps, they were more for CUVs, they don't go in the snow, etc., etc.

I've used TireRack for research for years, but have never bought anything from them. I think it's time to start. The Goodyear shop wants $330 per tire installed and the local guy wants $318 per tire installed for the OE tires. TireRack has them for about $217 each. Even factoring in shipping and somewhere in the neighborhood of $22 per tire installation (at the same local guy that wants $318 each), I'll be saving a considerable amount - about $250-$275.

 

[johnsmellsalot]

As long as your tires are the same size and speed rating, you'll be ok. Just make sure your car doesn't weigh more than what the tires are rated for. On the side of the tire, you may notice the words: MAXIMUM LOAD RATING 1,500 LBS @ 44 PSI. Do not exceed those specs.

 

[stephen9666]

The difference in weight capacity between 104 and 105 is just over 50 lbs. per tire.

Info taken from this link.

104 1984 lbs
105 2039 lbs

According to Wikipedia, the weight of a Jeep Commander is 4391 lbs.

Personally, I wouldn't have a problem going from 105 to 104 load rating.

Also, have you checked Discount Tire Direct? They have a smaller selection of tires, but generally better prices than Tire Rack.

 

[leeharvey418]

Your OE tires are a Euro-metric service description. There's no practical difference between a 245/60R18 105x and a P245/60R18 104x.

So yeah - the guys at Firestone are half right, but they're doing a pretty poor job of explaining that P-metric and Euro-metric service descriptions are, for all intents and purposes, interchangeable.

 

[CapriRacer]

Originally Posted By: leeharvey418
Your OE tires are a Euro-metric service description. There's no practical difference between a 245/60R18 105x and a P245/60R18 104x.

So yeah - the guys at Firestone are half right, but they're doing a pretty poor job of explaining that P-metric and Euro-metric service descriptions are, for all intents and purposes, interchangeable.


2nd vote on the difference between P metric and metric tires. Further explanation:

European and Japanese based Standard Load passenger car tires are rated at a maximum pressure of 2.5 bar = 36.3 psi, while P metric tires are rated at 35 psi = 2.41 bar. When these pressures are compensated for, the load carrying capacity is equivalent at the pressures specified by the vehicle manufacturers. This is just way too complicated for the guy at the average tire shop to understand - and even if he understands, it's still hard to relate.

For practical purposes, the 2 tires are equivalent. Where the problem comes up is when comparing Standard Load with Extra Load - XL tires are rated at 41 psi = 2.8 bar