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Posted

Ok guys/gals,

If I were to upgrade to larger wheels, what rim specs and tire size will I need that will not effect the speedometer?

For example:

Rim | lug pattern and offset? | Tire size?

16" __________ 275/70/16

17" __________ _________

18" __________ _________

19" __________ _________

20" __________ _________

etc....

Thanks in advance

Posted

for 18' rims, you would use a 285/60/18. That is what I have on my car. I'm not sure how the width affects the numbers in the tire size but my rims are 18x11. Since they are so wide, i pick up a lot of ruts in the road. You car probably won't drive as nicely with larger width.

Steve

Posted

Im not sure about affecting the speedometer by having bigger n wider tires. But im pretty sure it is. Because right now i have 23 x 10.5 with 305/35/23 on my 450

and while my 470 runnin 24 x 11 with 305/30/24 usin Pirelli Asimmetrico P-Zero.

I used to have "20 rims on my450 and i noticed that since i got the "23 seems when i drive the car little heavier~(Disadvantage)

While the advantage to have big rims and wider tires is by having bigger rims and less rubber means less friction and also u can feel the car more rigid to the ground

affect the car handling, so far here in so cal freeway after i dropped the LX "4 inch

to the ground i can go for 85mph on the 60 degree curve and the LX just stayed on the ground.

But my opinion changin bigger rims and wider tires wont feel much good as compare to the stock factory, ull lose the comfyness ,fuel economy unless if u tired of the look and want to look different then i have no word for it.

:cheers:

Posted

Find a spreadsheet (I use Excel) and paste the following in cell 'D':

=(((A1*(B1/100))*2)/25.4)+C1

In cell A insert the width of the tire (e.g. 275)

In cell B insert the aspect ratio (e.g. 70)

In cell C insert the rim diameter (e.g. 16)

Cell D will display the tire height in inches. Play with the values in cells A and B while increasing the rim diameter in cell C. If you want the speedometer to not be affected by tire size, you need to remain as close to stock as possible.

Or...you can just skip all the math and get a Truespeed calibrator to reset your speedometer.

Posted
Im not sure about affecting the speedometer by having bigger n wider tires. But im pretty sure it is. Because right now i have 23 x 10.5 with 305/35/23 on my 450

and while my 470 runnin 24 x 11 with 305/30/24 usin Pirelli Asimmetrico P-Zero.

I used to have "20 rims on my450 and i noticed that since i got the "23 seems when i drive the car little heavier~(Disadvantage)

While the advantage to have big rims and wider tires is by having bigger rims and less rubber means less friction and also u can feel the car more rigid to the ground

affect the car handling, so far here in so cal freeway after i dropped the LX "4 inch

to the ground i can go for 85mph on the 60 degree curve and the LX just stayed on the ground.

But my opinion changin bigger rims and wider tires wont feel much good as compare to the stock factory, ull lose the comfyness ,fuel economy unless if u tired of the look and want to look different then i have no word for it.

:cheers:

:wacko: Oh, now I get it. :chairshot:

Posted
Find a spreadsheet (I use Excel) and paste the following in cell 'D':

=(((A1*(B1/100))*2)/25.4)+C1

In cell A insert the width of the tire (e.g. 275)

In cell B insert the aspect ratio (e.g. 70)

In cell C insert the rim diameter (e.g. 16)

Cell D will display the tire height in inches. Play with the values in cells A and B while increasing the rim diameter in cell C. If you want the speedometer to not be affected by tire size, you need to remain as close to stock as possible.

Or...you can just skip all the math and get a Truespeed calibrator to reset your speedometer.

Dougjohn,

Coolness!!!! This is the rosetta stone of tire size. I've alway wondered how that worked. So then, on my '99 I have 265/75 16's which based on the math means a 32" tire? If I want a wider tire but not a taller tire, I can just juggle the ratio's and make sure I still end up with a 32" tire, right?

Thanks!

Posted
If I want a wider tire but not a taller tire, I can just juggle the ratio's and make sure I still end up with a 32" tire, right?

Yep, that's right. Juggle the ratios to get the size you want. Hope you find a tire that meets your needs.

Just as a FYI and for those out there who might not have found this on the 'net yet, metric tires sizes work like this...

Using 275/70 R16 as an example:

- the 275 is the width of the tire, in millimeters -- i.e. the tire is 275mm wide (aprox 10.8 inches).

- the 70 is the percentage of the 275mm that is the height of the tire from the edge to the rim. In other words, the distance from the rim to the edge of the tire is 192.5mm (or aprox. 7.6 inches).

- finally, the 16 is the width of the rim that the tire will fit on.

One final note -- regardless of the math, all actual tire sizes do not necessarily match the stated tire sizes. All manufacturer's sizes vary a bit and depending on sidewall flex (more side wall flex essentially shortens the tire height), the actual height will vary from manufacturer to manufacturer.

:cheers:

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