Fitting Bigger Tires

[hans1977]

Hi,

I have a Mazda Familia with 175/70/R13 tires, and i'd like to fit bigger tires with more air inside to compensate for all the bumpy roads with holes. What i'd like is not extreme, just 185/70 (or 65)/R15. I think the dimensions i'm thinking of would be fine at the rear, for sure, but it's much more unsure for the front. How will i know, in advance, if the new bigger tires will fit? And, yes, i know i will have to change the entire wheels, of course...

/Hans

[WinnieTheKhwai]

Don't do it. Bigger tyres will not do a whole lot for comfort (look into suspension tweaks for that one) but will:

* Increase fuel consumption

* Reduce wheel-torque

* Make your speedometer and odometer incorrect

* Anything but a very marginal increase leads to the wheels hitting the wheel arches in tight turns with a bump in them.

Of course adding a small lift to the suspension would get rid of that last issue, but overall there really is no point.

[culicine]

Don't do it. Bigger tyres will not do a whole lot for comfort (look into suspension tweaks for that one) but will:

* Increase fuel consumption

Not necessarily. It would depend on the overall weight. I went from 15" to 17" with no discernable change in FC.

* Reduce wheel-torque

Not necessarily. I got better acceleration with larger diameter wheels as the overall weight of them was less. That is, they didn;t require extra torque from the engine to turn them. I assume that is what you are referring to.

* Make your speedometer and odometer incorrect

Not necessarily. Depends on the overall diameter. 15" 195/65 will have close to the same diameter 17" 215/45. So the odometer and speedo are still accurate.

* Anything but a very marginal increase leads to the wheels hitting the wheel arches in tight turns with a bump in them. Again that depends on the wheel/tyre setup. Mine don;t rub lock to lock, but the 205 16" wheels I had on my city did rub, so I went back to 15" (which is still 1" oversize)

Of course adding a small lift to the suspension would get rid of that last issue, but overall there really is no point.

I think people do it as it looks better. Lowering the car with sports springs would potentiall cause more rubbing issues. I kept the same ride height and don't have those issues. I think they main problem is that the ride quality can suffer and road noise can increase with lower profile tyres.

[hans1977]

The conclusion of your replay would then be that bigger tires, particularly the ones i suggested, will not fit, right?

/Hans

Don't do it. Bigger tyres will not do a whole lot for comfort (look into suspension tweaks for that one) but will:

* Increase fuel consumption

* Reduce wheel-torque

* Make your speedometer and odometer incorrect

* Anything but a very marginal increase leads to the wheels hitting the wheel arches in tight turns with a bump in them.

Of course adding a small lift to the suspension would get rid of that last issue, but overall there really is no point.

[rixalex]

For your needs, forget bigger tyres.

Most people fit them just for the looks. Some might argue improved performance, but certainly not in the department you are looking at i.e. ride comfort.

[hans1977]

I thought bigger air volume would would absorb bumps in the roads better, but no, right?

/Hans

For your needs, forget bigger tyres.

Most people fit them just for the looks. Some might argue improved performance, but certainly not in the department you are looking at i.e. ride comfort.

[Crossy]

If you fit 15" rims you'll need lower profile tyres to maintain the outer diameter in order to fit (and keep the speedo correct). Low profile tyres tend to do the exact opposite to what you want

To get more air volume, retain the existing rims and get a higher profile tyre (175/80 maybe), but I'm not sure if they're available and I doubt the difference would be noticable anyway.

Improve the ride with suspension mods, trouble is softer springs whilst being nicer on the rough tend to screw up high speed handling.

Edited July 5, 2008 by Crossy

[tb86]

larger tires will effect your gas consumption, throw off your speedometer, maybe they will rub on the insides of your wheel wells, but the positives for having larger tires is that obviously you get added height at your differentials, a larger footprint that will equate to more traction, with larger wheels you have the ability to run a larger brake set up...

as for having trouble with bumpy roads, there are several solutions to the problem, change you shocks to a high quality shock such as billestien, or rancho, or you can always use a bypass style shock to prevent shock fade, the second and the easiest way of dealing with rougher roads is to lower the air pressure on your tires, i dont suggest this for hi speed scenarios, but its a verry old offroad trick to dealing with washboard roads, works like a dream. As for suspension lift kits be careful that you get a high quality one if you take that route many of the cheaper companies use leafspring packs that are much stiffer than the factory to help acheive lift, so do your research before you buy old man emu makes respectable set ups

[initiala4]

For 35-series tires, you will want a tire that is 277 mm wide

For 40-series tires, you will want a tire that is 243 mm wide

For 45-series tires, you will want a tire that is 216 mm wide

For 50-series tires, you will want a tire that is 194 mm wide

For 55-series tires, you will want a tire that is 177 mm wide

For 60-series tires, you will want a tire that is 162 mm wide

For 65-series tires, you will want a tire that is 149 mm wide

For 70-series tires, you will want a tire that is 139 mm wide

For 75-series tires, you will want a tire that is 129 mm wide

For 80-series tires, you will want a tire that is 121 mm wide

For 85-series tires, you will want a tire that is 114 mm wide

For 90-series tires, you will want a tire that is 108 mm wide

[hans1977]

I sort of gave up the idea about bigger tires as i have been unsure already from the beginning and did not boost my confidence by starting this thread.

I found four secondhand tires, of the same dimension as the old ones, manufactured 2007 week 43 in Thailand for 3100 THB. I estimate that there is about 7 mm left on each of them.

I managed to persuade the staff at the place to balance the front wheels, but not the rear wheels, as they were too convinced that it would be useless... I hope it will be alright anyway...

Afterwards i was happy to notice that less force is required to steer the car with the new tires.

Thank you all, for helping me to make up my mind!

/Hans

Hi,

I have a Mazda Familia with 175/70/R13 tires, and i'd like to fit bigger tires with more air inside to compensate for all the bumpy roads with holes. What i'd like is not extreme, just 185/70 (or 65)/R15. I think the dimensions i'm thinking of would be fine at the rear, for sure, but it's much more unsure for the front. How will i know, in advance, if the new bigger tires will fit? And, yes, i know i will have to change the entire wheels, of course...

/Hans

[mikethevigoman]

Hi,

I have a Mazda Familia with 175/70/R13 tires, and i'd like to fit bigger tires with more air inside to compensate for all the bumpy roads with holes. What i'd like is not extreme, just 185/70 (or 65)/R15. I think the dimensions i'm thinking of would be fine at the rear, for sure, but it's much more unsure for the front. How will i know, in advance, if the new bigger tires will fit? And, yes, i know i will have to change the entire wheels, of course...

/Hans

175-50-16 will be the correct size if you want to go up 2 inches, ride will not deteriorate,they will fit and the tyre height will remain unchanged,.