Would like to know if there is a range of tire sizes per vehicle or is one size per only. example i have a 2001 windstar p205/70/15 can i or better yet should i be fooling around going up or down in size just because im finding a so called DEAL????? another example i have a box truck on a 350 van chasis specs call for 215/85/16 but on it (when bought) fronr right: LT 235?85/16 front left: LT 245/75/16

Not everyone knows about tires. They can say whatever they like, or sell you whatever they might want to sell. it is up to you to tell them that you want and is the required sized tires for your vehicle.
You can also go oversized tires for your vehicle if you like. As long as they do not rub any areas of the vehicle when installed. That could be dangerous.

Shop around for tires, you want to get the best you can get for the lowest available price. Don't be fooled by some numb nuts that doesn't know a car tire from a bicycle tire.

I don't believe there would be a problem due to fit but this is difference in measurements.
The 75 diameter (across tire) is 28.88 in.
The 70 diameter is 27.95 in
The 75 width of tire is 9.25
The 70 width is also 9.25
The 75 circumference 90.72
The 70 circumference 87.82
The 75 sidewall height 6.94
The 70 sidewall height 6.48
The 75 revolution per mile 698
The 70 revolution per mile 721
The 75 speed at 50 and the 70 is 48.4
I can't see why it would not work.

Hello Projocs03,

Tires are typically measured tire width (sidewall)/tire ride height/wheel size. The differences of the two tire sizes you published are .4 of an inch difference in width/sidewall. And about .55 in over all diameter which would impact you revs per rotation. Depending on your wheel size.

Attached is a comparison of the two given the variable of 17" rim.

Stock Tire >Search Tires Tire 1 - 255/70R17 >Search Tires Tire 2 - 265/70R17 >Search Tires Section Width: - - Section Width: 10.03 in 255 mm Section Width: 10.43 in 265 mm Rim Diameter: - - Rim Diameter: 17 in 431.8 mm Rim Diameter: 17 in 431.8 mm Rim Width Range:
Rim Width Range: 6.5 - 8.5 in Rim Width Range: 7 - 9 in Overall Diameter: - - Overall Diameter: 31.05 in 788.67 mm Overall Diameter: 31.60 in 802.64 mm Sidewall Height: - - Sidewall Height: 7.02 in 178.30 mm Sidewall Height: 7.30 in 185.42 mm Radius: - - Radius: 15.52 in 394.20 mm Radius: 15.80 in 401.32 mm Circumference: - - Circumference: 97.54 in 2477.5 mm Circumference: 99.27 in 2521.4 mm Revs per Mile: - Revs per Mile: 669.8 Revs per Mile: 658.2* Source http://www.1010tires.com/TireSizeCalculator.asp?action=submit

I added the above link so you can research further or change any variables you need to know. However, the most important thing to understand is the impact of your speedometer. Different sizes will have different impacts. For example going to a bigger tire will show a slower speed on your spedo that your traveling.

Good luck

This depends a lot upon what size rims you have, and what your driving conditions will be. Generally, the type of tire that is already in use on the car should be fine (the tire type and size are printed on the side of the tire ... usually something like "P175 65R14" or something like that -- it's in big lettering on the sidewall). The "P" in my example is for "Passenger" cars ... the first number (175 in the example) is the width of the tire tread in Millimeters ... the second number (65 in the example) measures the depth of the tire -- the distance from the rim to the tread ... "R14" gives you the radius of your rim.
The width of the tire affects the handling of your car (wider tires give you better handling) but can also contribute to road noise -- the wider the tire the noisier it is. If you've heard the noise from a Jeep with mudders (extra wide tires for driving in muddy conditions), then you understand the noise. With a Corolla you will probably not be facing too many off-road situations, so between 145 and 185 should be fine for a first number.
With a corolla, I would always recommend a passenger tire ... other ratings are for trucks and load-bearing vehicles.
The depth of the tire can also affect handling and road noise. The second number (65 from the example) gives you the depth. If you are looking for low-profile tires, this would be a smaller number. Although this does affect the handling and noise, it is mostly about the look of the tire. If you desire to have a family-car look, go far something in the range of 65 ... A little more or less will not have much effect that you will notice, but a larger number will make the car jolt less whan you hit a pothole or a bump in the road.
"R14" from the example is the most important number, and the only one that cannot change without changing the rims. This is the radius of the rim, and MUST match or the tire will not fit, or will pop off the rim while driving. Read the sidewall of the tires you have now, and use the same R number. Generally, anyone mounting tires will make sure that you have the right size before they will put the rubber on the rim for you -- it is as dangerous to mount a wrong-size tire as it is to drive on one.
If you have more questions about your tires, I would recommend visiting a tire retailer and speaking with someone directly -- they are generally well trained about tire specifications, and can give you more detail about the effect that each aspect of a tire will have on your driving experience. Having driven a few Corollas, I always used P175/65R14 on mine (I think it is pretty standard) but please be sure to check your tire to make sure you have the same size rims.

The tire size depends on the vehicle trim level. Below are multiple trim levels and their respective tire sizes.

ES 235/75/15
LS 255/70/16
Limited 255/70/16
XLS 255/70/16
XS 255/70/16

The best thing to do if the vehicle is available is to inspect the tire sidewall for what the current equipment is. There is also typically a sticker in the driver door jamb, center console or glovebox stating the proper tire size & inflation.

Yes...
The tire sizes are important on any 4X4 vehicle... IF you engage the 4X4 ... or is you have an AWD vehicle...

If the tires are different sizes , front and rear... then the front and rear axles will turn at different speeds... not in sync with the gearing of the transfer case.

Unless this vehicle is being driven on snow , ice or mud.... while in 4x4 mode... this is very bad.... for axles and transfer case...

Go to your vehicle with a pad and a pencil, look carefully at the sidewall of your tires and you will see what the tire sizes are for your truck, they will look like this...example only....P225 75 X 15.
The 225 represents the tire height, the 75 is the width across the tire, the 15 is the size of the rim you have on the vehicle.
My example size may be the size you have, but double check it to be sure.

Original Equipment Sizes for 1999 Ford Windstar / LX
Original Equipment Size 1: 205/70-15
Original Equipment Size 2: 215/70-15

Original Equipment Sizes for 1999 Ford Windstar SE Original Equipment Size 1: 215/70-15
Original Equipment Size 2: 225/60-16 / SEL

Hope this helps

Inside your drivers door when you open the door there is a tag for your tire sizes. You can look at the other tires and get the size that already on the vehicle...235\70\R20. example.. Look for numbers like these

If you want to know the correct tire size for your vehicle. Open the drivers door and look on the edge of the door under the latch. You should find a data plate that will tell you size of tire for your van and proper air pressure for front and back tires.