I would appreciate some help with this!

I have a 2002 S10 Blazer 4.3L 4WD LS that needs some new tires. The original door sticker shows the correct tires as P235/70R15 but all the retail tire sites I'm searching show P235/75R15 as the correct tire size for this car. Some of the tire sites won't even let you get to the Checkout page, after entering my model year car details, if I select the 70R15 tires stating that these tires don't fit your car!

What up with this? And what tires would you suggest I buy for this car? P235/70R15 OR P235/75R15

 

I've always gotten 235/75r15 for mine as stock. I will be going bigger now that I have a lift kit...

but stock size for me is 235/75r15

 

For at least my 1999, the default stock tires are the 235/70R15 as indicated in the door jam and in the 1999 Blazer Product and Ordering Guide. The Z85 "Touring Suspension" option had 235/75R15 tires. The 235/75/R15 tires are a very popular "upgrade" people will do for the tad more height they provide over the 70-series tires.

 

Thanks Don! Thanks Christine!

After digging in to everything I could find this afternoon on-line, I decided to go with 4 new P235/70R15 tires. That's the size that's on there now and that's what the OEM sticker on the door jam says is correct for the car. Plus, there shouldn't be any discrepancies with the speedometer either! Another plus is that while there are a couple of different brand tires currently installed on the car, the newest and best of the four and will be saved as the spare, is the same brand and model as the four tires I'm planning to purchase. SO all four tires AND the spare will all be the same size and brand of tire!

I appreciate your replies! BT

 

Glad the info was useful. Here is something else that can be helpful: https://tiresize.com/calculator/

One of the types of information this calculator gives is differences in the actual speeds depending on the different tire sizes. In your case, the difference between the 70 and 75 series is about 3%.

Best

 

Oh. Since the body lift I am on 30/9.5 BF AT. I've noticed my mpg got smaller[1] (a change is in between 10-20%), . On one hand it is a bigger tire, so the velocity is actually higher than shown and affects calculated result. But, on the other hand, body is higher, what mess up aerodynamics. From these two factors, using Your calc seems the aerodynamics plays more significant role.

[1] average mpg based on the ECU calculation, not the real one, calculated on odometer records.

 

The only "stock" tire around where I live is the P235/75R15...

 

Here is the door jam sticker for my Blazer. The Z85 suspension option had the 75 series tires, at least in 99. (Hey look, my truck is 20 y.o.! One more year and it can drink at a bar. )

 

Thanks again Christine! The figures on the calculator are very close to what I calculated. (i.e. approximately 1" difference in height and about 3.5%)

The info on your sticker is essentially the same as the door jam sticker on my 2002.

Thanks Mike! I think you may be correct about the aerodynamics playing a larger role in decreased mileage!* Since most of the miles (250K) on my Blazer have all been on paved roads, I have no interest or need for any additional body height or clearance.

Thanks Go Chevy! Most of the on-line tire sites I visited listed the 75R15 as OEM stock too. I think this is probably due to the 75R15 being a much more popular tire for later model Blazers (?) and many other SUVs.

Thanks again to all who replied! BlazerTom
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