Tire size and Speedo error calculator

[CaliforniaKnight]

While upsizing say from 13" to 14", we can keep OD of the 14" as per the original company norms, but what worries me is the width of the rim that is increased, say from4.5J - 5.5J. Isn't that a cause of worry??

[rks]

Originally Posted by kpzen

hey Rtech

I agree low profile tyres will give you a harsh ride.....
But... I'm facing a different problem with rim width size...
I upgraded my zen tyres to 165/65-13 with stock steel 13x 4j rims....I know the width of rim isn't correct as per rim size calculator...
My handling n braking become pathetic....and driving at high speeds have become scary to say the least...
I just want to know the how a wrong size rim affects the running of a car...??
Will it have any affect on any other parts like suspension and of course tyres..

KP

Same question for my Santro. Want to upgrade from stock 155/70-13 radials with stock steel 13 X 4j rims to 165/65-13 tubeless. I plan to change my steel rims to alloys. So question is what width should I use? Is 13 X 5j available or should I stick with 4j? Speedsatya's link suggests that the rim width in this case should be in the range 4.5-6. But what are the choices available, and how does this affect performance?

The other thing that I am worried about is stuff like fuel economy, top speed, long-term effects on suspension. From Speedsatya's link and other sources, it appears that if the rolling radius (or outer diameter) comes down (which is the case with my proposed upgrade) then the acceleration will increase, but fuel economy and top speed will come down. By how much? This seems to be a complicated calculation, because when one changes from steel rims to alloys, the weight comes down and so this ought to compensate in case of FE and top speed.

Thirdly, regarding the shift to tubeless tyres. Many local tyre shop guys are telling me that tubeless tyres can easily tear while going over sharp stones, etc., as they softer than the stock all-season tyres, and may even come off the rims. Secondly, it is more difficult to find tyre repair shops that can handle tubeless. So this has again gotten me confused, since the roads in Pune and on the Mumbai-Pune route (which I have to take every week) are horrible and full of pot-holes/sharp stones during the monsoon season.

But I have almost made up mind on the upgrade, with 13 X 5j rims if available. The fact that tubeless tyres are safer on the highways with regard to the puncture/burst scenario is the primary reason. Any further suggestions are welcome.

Regards, rks

[maxbhp]

Originally Posted by CaliforniaKnight

While upsizing say from 13" to 14", we can keep OD of the 14" as per the original company norms, but what worries me is the width of the rim that is increased, say from4.5J - 5.5J. Isn't that a cause of worry??

Increasing width increases the contact patch thus increasing the rolling resistance .... It will definetely take a toll on perfomance other than that I dont think there is any other problem if the OD is kept as per OE.

[autopsyche]

(Edit) Oops wrong thread.

[iraghava]

Originally Posted by rks

Same question for my Santro. Want to upgrade from stock 155/70-13 radials with stock steel 13 X 4j rims to 165/65-13 tubeless. I plan to change my steel rims to alloys. So question is what width should I use? Is 13 X 5j available or should I stick with 4j? Speedsatya's link suggests that the rim width in this case should be in the range 4.5-6. But what are the choices available, and how does this affect performance?

The other thing that I am worried about is stuff like fuel economy, top speed, long-term effects on suspension. From Speedsatya's link and other sources, it appears that if the rolling radius (or outer diameter) comes down (which is the case with my proposed upgrade) then the acceleration will increase, but fuel economy and top speed will come down. By how much? This seems to be a complicated calculation, because when one changes from steel rims to alloys, the weight comes down and so this ought to compensate in case of FE and top speed.

Thirdly, regarding the shift to tubeless tyres. Many local tyre shop guys are telling me that tubeless tyres can easily tear while going over sharp stones, etc., as they softer than the stock all-season tyres, and may even come off the rims. Secondly, it is more difficult to find tyre repair shops that can handle tubeless. So this has again gotten me confused, since the roads in Pune and on the Mumbai-Pune route (which I have to take every week) are horrible and full of pot-holes/sharp stones during the monsoon season.

But I have almost made up mind on the upgrade, with 13 X 5j rims if available. The fact that tubeless tyres are safer on the highways with regard to the puncture/burst scenario is the primary reason. Any further suggestions are welcome.

Regards, rks

Ok Rks here we go

1. The benefits of changing to alloys as regards to FE are hardly visible it makes a difference of very small percentage and unless you calculate the fuel consupmtion down to the last ml I don't think you will be able to see any major difference.

2. Tubeless tyres do not tear easily but this also depends on the brand you are going to use. I have had bad experiences with Goodyear F1's but Bridgestones & Michelin's have been absolutely perfect. As for repairs don't worry they don't get punctured that often and when they do and you see the gradual air loss then all you have to do is fill up air and will work fine for another 250-300 kms. The gradual air loss makes tubeless tyres very easy to handle as you can fill up air anywhere and then drive on till the next proper tyre shop without risking tyre failure.

3. Rolling radius or OD is based on the tyres you choose and has no relation with Alloys. 165/65 R13 are perfect for a Santro and I have run 3 sets of tyres of this size without any issues at all. Let me show you:

155/70 R 13 - 273.6 Rolling Radius
165/65 R13 - 272.35 Rolling Radius

Difference = -0.46% (which is within the recommended tolerance of +1to-3%)

Speedo reading will be 70 mph whereas actual speed will be 69.68 mph.

So you can upgrade to this size without any worries. Do update us on your feedback once you do the upgrade and tell us whether you like it or not.

[rks]

Thanks, iraghava. My Bridgestone S322 tyres have done 30000 kms and are now 5.5 years old. Tread is still fine. So will probably let the car run another 5000 kms and then go for the suggested tyre upgrade (with Aura alloys), maybe around September. Eagerly looking forward to it and will definitely get back to this forum with my experience.
Regards, rks

[abhibh]

Hi,

Nice guides cleared almost all my doubts.. Just One question.. Can someone tell me what do you mean by 4J and 5J also what differnce will it make if i fit 5J on a 4J stock ?

Thanks.

[hydrashok]

Originally Posted by iraghava

2. Tubeless tyres do not tear easily but this also depends on the brand you are going to use. I have had bad experiences with Goodyear F1's but Bridgestones & Michelin's have been absolutely perfect. As for repairs don't worry they don't get punctured that often and when they do and you see the gradual air loss then all you have to do is fill up air and will work fine for another 250-300 kms. The gradual air loss makes tubeless tyres very easy to handle as you can fill up air anywhere and then drive on till the next proper tyre shop without risking tyre failure.

Ahhh... I was just going to ask that question. I have 205/50 R15 Pilot Precedas on my Palio. They're my first set of tubeless tyres, and this (punctures) is something I've been concerned about. (Especially because my spare tyre is the OE unit with OE steel rims. I don't want to have to get it out except in a REAL emergency).

[vikram_d]

Originally Posted by abhibh

Hi,

Nice guides cleared almost all my doubts.. Just One question.. Can someone tell me what do you mean by 4J and 5J also what differnce will it make if i fit 5J on a 4J stock ?

Thanks.

4J & 5J are the widths of the rims. It simply means that the width of the rim is 4 inches or 5 inches as the case may be.

[dilipkumar7278]

here is another site for tyres and related articles....

www.1010tires.com

[DRIVEN-TWEEL]

for my skoda the actual size is 195 65 15 or 205 60 15. according to the upsize chart the actual size in 17 is 225 45 17, but i put 235 45 17 which gives me better profile than 225. i want to know how much difference would this cause. would the reading increase or decrease..

[vijayakumar]

i've a swift car and i got to change my stock wheel which is 14" to 15" wheel size ...i just want to ensure that ,will it reduces the fuel mileage of the car...

[vijayakumar]

i need to put low profile tyres for my swift car ..i thought to go for yokohama but all say that ,there is a tyre noise and the puncture rate is more due to softer in tyre stiffness ..so can any one suggest which tyre i would choose...

[iraghava]

Originally Posted by vijayakumar

i need to put low profile tyres for my swift car ..i thought to go for yokohama but all say that ,there is a tyre noise and the puncture rate is more due to softer in tyre stiffness ..so can any one suggest which tyre i would choose...

What size do you want to go to? Do a search on the forum regarding Swift upsizes, you'll get a lot of replies to your questions.

[adisseril]

what is the ideal size of rim/tyre for maruthi esteem