View Full Version : OEM Tires

Still Crusin
03-04-2003, 01:06 AM
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.

James Kanteraki
03-04-2003, 03:28 AM
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


03-04-2003, 04:45 AM
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..

03-04-2003, 04:59 AM
The Supercoupes actually came with W rated tires which were rated for 168MPH. Z rated = 149+

03-04-2003, 05:16 AM
oh.. i wasn't sure about those, but i knew the 89 had V-rated.. thats good to know.

03-04-2003, 06:15 AM
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.


fast Ed
03-04-2003, 11:23 AM
Originally posted by 1BADSC
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 (http://www.tirerack.com/tires/tiretech/general/speed.htm) 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.

Ed Nicholson

03-04-2003, 12:46 PM
my mistake, my tire shop looked it up in there book and it listed W rated as the factory original.

03-04-2003, 02:05 PM
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)

03-04-2003, 02:15 PM
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.

03-04-2003, 08:24 PM
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)

03-04-2003, 11:55 PM
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.

Still Crusin
03-09-2003, 12:26 AM
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.