OEM Tires

Still Crusin

Registered User
Was wondering if anyone can give me some insight on how car manufacturer's decide what tire they are going to put on a particular vehicle?
I'm getting ready to replace my tires again and I've been trying to educate myself a little more in this area. Been cruising the board seeing feedback on various tires. My 94 originally came equipped with Goodyear Z-rated tires, which seemed nice, but unfortunately I had a lot of flats with those since those tires seem to pick-up everything. I think it was a little overkill anyway putting z-rated tires. I replaced them with H-rated touring tires, Firestone, and I've had good success with them, though they don't grab wet pavement well when you punch it from a stop. I'm thinking about going back to a Goodyear tire and maybe a V-rated tire. Not sure what size I want to go with. I still have stock rims.
 
tires

don't know how they choose what tires to put on but..

bird original size was 225/60/r16

i can tell you this though
I got my bird used and it came with some H rated tires. Man, i was scared to drive that thing when it was raining. I tried out some Z rated BFG's. Now at least i feel "relatively" safe when it rains.

I think they took water into consideration when choosing tire type


jim
 
I am not entirely sure how they choose.. and don't quote me.. but, I think its based on the purpose of the vehicle, whether is an economy car, a compact, luxuray or a sports car.. The rating would go with the speed that the vehicle can reach. Since our cars are fast vehicles and need a tire that can handle the speed and have excellent traction the manuf choose to put Z- rated tires.. It wasn't always like that.. the 89 + came with V- rated tires.. (which the car could easy spin) Z rated tires last the least of any other rating.. because they are designed to grab the road hence why you get so many flats. (i feel your pain) V-rated last longer and don't pick up as many flats as the others... but you do sacrifice traction.... this is just my opinon. hope this helps..
 
The Supercoupes actually came with W rated tires which were rated for 168MPH. Z rated = 149+
 
Speed rating in and off itself shouldn't necessarily be the deciding factor... I think even S rated tires are rated for 105 mph - and that is 105mph of continuous use... something you really aren't going to find in the states. I can't remember the entire list and general wisdom has it that you don't to go with a lower speed rating than OEM... but at the same time, chances are if you were to get a decent quality H, V, W, Y, or Z you won't have too much of a problem.

If you go with anything smaller than a 225/60/16, the new tires weight rating will be less than original. I'm using 225/55/16s on the front that are rated for about 100 or 150 pounds less per tire than stock, and 255/50/16s on the rear, which I think are rated for either the same as stock, or a little bit more.

Paul
 
1BADSC said:
The Supercoupes actually came with W rated tires which were rated for 168MPH. Z rated = 149+

That is not correct. The earlier cars had V-rated tires, which was the highest rating available back in 1989. The 94 - 95 cars had Z-rated tires, I don't think W-rated tires were even available in 1994, if they were, certainly not in a tall size like 225-60-16.

Take a look HERE for a good explanation of the various speed and load ratings.

For the SC, the car was capable of 140+ mph from the factory, so Ford chose to put suitable tires on it, rather than a top-speed limiter.

cheers
Ed Nicholson
SCCoO
 
my mistake, my tire shop looked it up in there book and it listed W rated as the factory original.
 
i have T rated 225/60/16 on my car right now, they are rated to 118+

they do spin a little easier in the rain, but then again, with 25k miles on them, they still have 8/32 of tread left (11/32 when new)
 
Just FYI for those speed ratings.. Buyer be-aware that just like 4WD, sometimes you're paying for something which you'll never ever need or use ;) ;)

The rating are for SUSTAINED operation at the rated speed. So, for a Z rated tire, unless you're actually road racing, its just prestige. An H rated tire is sufficient for any and all driving. Of course, tire manufaturers today make a top quality and very affordable V tire for under $100. That wasnt the case 10 years ago.
 
Speed Ratings

A speed rating applies to more that just speed. To quote one of my fellow employees, it should really be a "performance" rating. Everyone knows that the average person doesn't drive 149+mph but the speed rating will affect cornering, braking, and overall handling of the car. Keep in mind what type of weather you will be driving in and pick a good tread pattern to fit that climate. Also, keep in mind the ratings for temperature, traction, and treadwear. They can be useful, but sometimes don't tell the whole story; the treadwear number is probably the most useful of the three. Most tires this size will be able to handle the weight of our cars but it's not a bad idea to double check the load rating. By the way, I'm an engineering co-op for Cooper Tire, check out there website @ www.coopertire.com we really have some great tires to offer at good prices. (Sorry for the advertisement)
 
only bad thing about treadwear is you can't cross compare. A 300 in a Goodyear is not the same as 300 in a Firestone. Each Company measures this a little bit different. Only way to be sure is compare in company, if you have every had the brand before.

I have Nitto NT450's in a 245/50 with is about 1" less then our 26.5" 225/60 size. I said I would never go with this size becuse of the added 4X4 look, but they look and act 100% better with the wider stance. I have not tried them in the rain yet, go figure it rained almost everday for the last couple weeks and since I put them on no rain at all, but eveything else has been better. I expected this as I had Crapyear GT2 and hated them. No traction in either wet or dry.


As for how a Car company puts a tire on, as stated before they have to match the tire with what the car will do, either by putting on a high speed rated tire or with a speed limiter, but they also have to account for the cornering ability of it. Kinda like a Miata, not going to win no top end battles, but with some good tires with handle with some of the more $$ cars out there.
 
Thanks for the info

Definitely some good points made on this subj. The speed rating aspect is not so much of an issue with me. I know for a fact my car came new with z-rated tires on my 94 cause I'm original owner. I just thought it was a little overkill, cause I've never driven the car to its top speed (came close a couple of times), therefore don't really need z-rated. However, I do believe the rating does make other performance impact such as handling, etc.

I've thought about going with a taller than stock tire in the rear to better fill the wheel well. It seems most people lower the car, rather than get a taller tire. Plus, I know there'd have to be an adjustment to keep the speedo accurate. I wouldn't mind having the car lowered, but I have other priorites with it rignt now and I also probably need to replace rear shocks. I'm having a lot of trouble with the ARC right now and am debating wether I want to keep that system or not. I do like it when it's working, but it's been a pain lately.
 
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