Relationship between speed rating and load rating?

[IndyIan]

So I am looking at some BFG Sport Comp2's for my Focus.
The largest size they have for 15" rims is 195/55 which has a V speed rating(149 mph) but only a 85 load rating. The Focus comes with 87 load rated 195/60R15 but with a T speed rating (118mph)
So with the Comp2s I am down 65 lbs per tire in load rating, but am up quite bit in speed rating. Also the Comp2's have a max inflation pressure of 44 psi and the load rating is tested at 35 psi, so I could run them at a bit higher pressures.
I've been reading Barry's tire site and it seems to me that the Comp2s could have a 87 load rating if they only tested them to the T speed rating?

The Comp2s are designed to survive at the track vs the cheapo 3 season tire the Focus comes with. Also the placard on the Focus also says 32 psi which means it doesn't need the full capacity of the 87 load rating.
Seems to me, everything points to the Comp2s at 35psi to be fine on my car, and most likely an upgrade in load capacity. I'd suspect the Comp2's would hold up much better if I was running 90 mph in desert heat (which I never do) than a cheap T-rated all season with proper load rating.

 

[Colt45ws]

The P195/60R15 @ 32psi has 1146lbs load capacity
The 195/55R15 @ 36psi has 1134lbs capacity.

I think you'll be fine.

 

[RedOakRanch]

High speed is more stress so less load...

 

[69GTX]

I did a lot of research on summer performance tires before buying my BFG Comp 2's two years ago (good test drive ratings, good consumer ratings). And they are priced right compared to the next step up which is a lot more money. My 275/40/17's cost $139/tire which included everything (sales tax, 4 wheel alignment, etc.).

Don't forget to use the $70 BFG rebate that is applied a couple times a year. Hopefully, that applies in Canada as well.

 

[IndyIan]

Well I'm feeling better about getting them now. A few more facts in their favour.
Originally Posted By: 69GTX
I did a lot of research on summer performance tires before buying my BFG Comp 2's two years ago (good test drive ratings, good consumer ratings). And they are priced right compared to the next step up which is a lot more money. My 275/40/17's cost $139/tire which included everything (sales tax, 4 wheel alignment, etc.).

Don't forget to use the $70 BFG rebate that is applied a couple times a year. Hopefully, that applies in Canada as well.

We get $50 off, but I guess that's better than nothing. I've been on the Miata forums a bit too and they like them in my size over anything else except the 200 wear rating tires. My other choice was S.drives but they seem to have less grip in the wet and more noise so I thought I might as well get the Comp 2s.

 

[69GTX]

I would say the only real negative on the Comp 2's is road noise. They aren't a quiet tire, at least not as quiet and comfortable as Michelin, Continentals of a similar rating. I'd rate them "fair" in that regard. It's really their only draw back other than not being a winter/all season tire. I have no problem with the noise though. Some of the other versions of BFG performance were really noisy. The KD/KDW line comes to mind if I recall correctly.

 

[IndyIan]

In 15" the pickings are starting to get pretty slim. Michelin especially seems to draw the line at 17".
I test drove a SRT4 neon with new KDW's a few years ago and they were quite loud, too much for me for a DD, but it seems the new BFG's are reasonable. This isn't our road trip car anymore and I'm going to do some autocross this summer, so I thought I might as well get some half-grippy tires as I'm not going to buy any 200 treadwear autocross specials.
I may end up having the best tired H-stock car so I might end up doing ok on our tighter courses, once PAX works it magic.

 

[69GTX]

The Comp2's are a lot more than half-grippy. That's one of their best features for an "ultra-high performance" summer tire. In that category I think they compete well with the higher cost "max performance" tires. I also considered the Nitto 555's because of their low price and fairly strong following. But, once all discounts were considered, the BFG's and Nitto were similarly priced.

 

[IndyIan]

I was a bit surprised though in the tirerack tests that this group of tire maxes out at about .9g in cornering and the next group up gets around 1g. I thought the Comp 2's might get a little closer, but I think for the wagon, much more sticky tires might have it on its roof anyways.
I used to run old r-comps on my old Neon and they stuck, seemly much better than any street tire at the time, but that was maybe 6 years ago so I guess the tires are all getting stickier.
Against the be best tires available in stock class autocross, I read the Comp 2s get killed, but best tires are a little too extreme for DDing for me, and they cost more, and I want to keep rubber side down.

 

[69GTX]

Indylan, I'm curious. What are considered the best motocross tires for the stock Neons?

 

[dailydriver]

As stated, the Comp 2s are much stickier than their 340 tread wear rating would suggest (I have them in 255/50-16 on my summer wheels).

But as was also said, they are not even close to the stickier 200 tread wear class (BFG Rivals/Bridgestone RE71Rs/Nitto NT-05s/Dunlop Direzzas/Hankook RS3s/etc.) of current 'street class' autocross tires (which are more likely 120-140 tread wear rated grip, regardless of what's imprinted on their side walls).

Let alone being in the same universe (as far as ultimate grip goes) as the 100 tread wear donuts (Nitto NT-01/Toyo RA1 & R888), or the 0-80 tread wear gumball, 'real R' compounds (Pilot Sport Cup & Cup2s/Pirelli Trofeo Rs/BFG R1s/Hoosier A7s & R7s/etc.).

 

[IndyIan]

Originally Posted By: 69GTX
Indylan, I'm curious. What are considered the best motocross tires for the stock Neons?

Like dailydriver said above, for a SCCA autocross, to remain in a "stock" class you have to use tires with 200 tread wear or more, so now there are a bunch of very sticky tires with a 200 tread wear rating.
If I was going to buy tires just for autocross one of those tires would be what I would get, but I also want to DD on them and something like this is a bit too extreme for me atleast, just to burn up doing 55 miles a day.

 

[CapriRacer]

IndyIan,

I get the impression the reason you are opting for these SportComp2's is for autocrossing. Is that correct? If not, why?

But to answer your question: In theory, the load rating and the speed rating are 2 separate items. In reality, a higher speed rating tire has better endurance than a lower speed rated tire - as does a higher load rated tire. So in theoretical engineering terms, I see speed rating and load rating as interchangeable. DISCLAIMER: That last sentence should be ignored by 99% of the folks who read BITOG. It is meant as a comment on the way reality works and not as a way around using a size tire not listed on the vehicle tire placard!

 

[IndyIan]

Originally Posted By: CapriRacer
IndyIan,

I get the impression the reason you are opting for these SportComp2's is for autocrossing. Is that correct? If not, why?

But to answer your question: In theory, the load rating and the speed rating are 2 separate items. In reality, a higher speed rating tire has better endurance than a lower speed rated tire - as does a higher load rated tire. So in theoretical engineering terms, I see speed rating and load rating as interchangeable. DISCLAIMER: That last sentence should be ignored by 99% of the folks who read BITOG. It is meant as a comment on the way reality works and not as a way around using a size tire not listed on the vehicle tire placard!

I am going to autocross with them and run them in the summer, basically 6 months of the year. I find I change to winter tires early enough to never run my 3 season tires in the snow anyways as mine are always terrible...
The Comp 2's I think are as extreme as I want to go on my DD, in terms of noise, tread wear, and cost. I need new summer tires anyways and these cost no more that a mid range 3 season and will have much more grip in the wet and dry.
I find my winter tires, yoko IG52c's quite good in terms of noise and wear so running them a bit longer in the shoulder seasons isn't a problem IMO.

 

[dailydriver]

Originally Posted By: IndyIan

^^^BFG REALLY NEEDS TO release these in more sizes!

 

[UG_Passat]

Originally Posted By: IndyIan
So I am looking at some BFG Sport Comp2's for my Focus.
The largest size they have for 15" rims is 195/55 which has a V speed rating(149 mph) but only a 85 load rating. The Focus comes with 87 load rated 195/60R15 but with a T speed rating (118mph)


There's no relationship between speed rating and load rating.

There is a relationship between tire size and load rating.

The 195/55r15 is typically 85 Standard Load with all speed rating. Some 84's are available.

Why did your car come with 87? If it's a factory tire, it very well could have been something Ford specifically wanted from the tire manufacturer.

another example....
my car came with 235/45r17 tires and you can find 94 and 97 load rating tires (both standard & extra loads). When I put 18" wheels, with 235/40r18, 95 LR is what you typically see in that size (standard and extra load)

 

[CapriRacer]

So a couple of side issues:

Yes, the load rating is pretty closely related to the tire size. This is determined by tire standardizing organizations. Unfortunately, there are many tire standardizing organizations and they don't exactly agree.

You would think that since Physics is involved, there are be one and only one way to determine the load rating of a tire - and that is only sort of true. Not only are there different assumptions made in trying to figure out how this stuff works, there is also the ever evolving technology in our ability to analyze - PLUS, once a standard has been published, you don't exactly replace it with something contradictory. Some of these standards are based on stuff analyzed in the 1930's.

If you were to look carefully, you will find that there are 3 different ways to calculate the load rating of a tire: The American version, the European version, and the Japanese version. These are ever so slightly different, but are all in the same ball park and for practical purposes aren't really different answers.

If you go look at Tire Rack, you can see these differences. The obvious one is the use of the letter "P" in front of the tire size. That's the American version. The other 2 versions are not as easy to identify the origin, but it is obvious they are different.