18" tyre size/ price/ comfort

cantdecide

hello all.

I'm trying to find a pair of 18" tyres for a relative. motivator is first and foremost comfort then price. performance, longevity etc. aren't a big deal, just comfort. at the moment he has 245/ 40 R18 and they're a little too low.

Car is a GS300 so there's no issue of scrubbing and i suspect he could go much higher and wider if need be.

what tyre size is cheapest? i know that nearly identical sizes can sometimes be twice the price (depending on brand of course).

is it true that wider tyres are in fact harder on the road or is that pub talk?

is there any particular tyres which are designed specifically for comfort?


there's no need for any smart alecs to state the obvious that 18's will always be stiff. i'm trying to find a happy medium between the inevitable low profile compromises and rock hard, over-priced long life performance tyres.

Anan1

There's not really a lot he can do to improve comfort without changing the rims. As the overall radius of the tyres has to remain the same, the only way to increase sidewall depth is to decrease wheel size. An ideal solution would be if he could find a GS300 owner on 16"s who wanted to swap wheels..

cantdecide

cantdecide wrote:

there's no need to state the obvious that 18's will always be stiff. i'm trying to find a happy medium between the inevitable low profile compromises and rock hard, over-priced long life performance tyres.

i was trying to avoid this.

the car won't blow up if you put on higher profile tyres. a carefully selected brand and size will minimise discomfort and won't cost the Earth.

Anan1

cantdecide wrote:

i was trying to avoid this.

the car won't blow up if you put on higher profile tyres. a carefully selected brand and size will minimise discomfort and won't cost the Earth.

Higher profile tyres on the 18" rims will increase the overall radius of the tyres. This may or may not foul the arches; it will definitely mess with the gearing and leave you with an inaccurate speedometer. See my last post.;)

JoeA3

I'm afraid Anan is right... if you do as you suggest, the overall wheel diameter will increase, meaning the speedo will be inaccurate, (leading to mileage being out) gearing won't be right, etc, etc

Lex Luthor

before you go changing your tyre sizes, have a look here

http://www.miata.net/garage/tirecalc.html

cantdecide

let me start again. :rolleyes:

is there an optimum size and brand of tyre that won't cost an arm and a leg and will decrease risk of discomfort as far as reasonably possible?

if you have something productive to add- thanks you very much. if not, please refrain from stating the obvious. unless you just like the sound of your own keyboard clicking???

we all know what happens when you change the size of a tyre but to hell with it- i'm probably going to do it anyway.

ps 40 to 45 means discrepancy of 2mph at 60mph by my calculations

maidhc

cantdecide wrote:

is there an optimum size and brand of tyre that won't cost an arm and a leg and will decrease risk of discomfort as far as reasonably possible?

The optimum size for comfort is the one with the tallest sidewall! I think that has been said though!

The pressure in the tyre will have a bigger bearing on the harshness of the ride than the brand of the tyre. But having the pressure low will create more problems than it will solve.

cantdecide

very true. he had these deflated a little when he got it first and it handled very badly and was no more comfortable

JoeA3

@ cantdecide - no, I don't much like my keyboard, I was only trying to be helpful, yet you still seem to have trouble grasping simple maths/physics - i.e. the only way to properly solve the problem is smaller rims.

Eoin

JoeA3 wrote:

@ cantdecide - no, I don't much like my keyboard, I was only trying to be helpful, yet you still seem to have trouble grasping simple maths/physics - i.e. the only way to properly solve the problem is smaller rims.

I think what he was trying to say - although in a very snotty manner - was that he was looking for a brand of tyres with the same figures that may be more comfortable than other brands. Then again, I could just be loving the sound of myself typing...

unkel

cantdecide wrote:

unless you just like the sound of your own keyboard clicking???

People are genuinely trying to help you and this is how you repay?

cantdecide wrote:

40 to 45 means discrepancy of 2mph at 60mph by my calculations

Yes about that. A bit less than 4%. So come to sell it with 96k on the clock there is actually 100k on it. Nobody will probably find out, but it is illegal to sell a vehicle where the miles on the clock are not the same as the miles driven by the car

cantdecide

unkel,

thanks for that. isn't there is a difference between speedo and the actual speed of a car with new tyres and oldish tyres anyway? i've also noticed that if you look at the exact same size tyre in a couple of different brands, they all seem to have slightly different heights. knowing this, isn't it almost impossible to tell a car's TRUE mileage.



(ps Unkel, they're answering a question i haven't asked. the last line of my original post was to prevent this from happening. i know beggars can't be choosers but i think it's rude to part read a question before you answer. if i don't know the answer to a question, i keep the way clear for someone who does. someone else might also benefit from this knowledge. but in this instance, people read "18's" and their first instict is to stop reading the question and just blurt out the old cliches. i appreciate anyone who tries to help but this helps no one, this is the mindless babble of the bored).

So- if someone knows how to minimise the hardness of an 18" wheel- i want to hear from YOU!

JoeA3

the only mindless and downright rude "babble" I've seen in this thread has come from you.

unkel

cantdecide wrote:

isn't there is a difference between speedo and the actual speed of a car with new tyres and oldish tyres anyway?

Yes on a 245/40/18 a brand new (presuming thread of 8mm) tyre has a nearly 2% longer circumference compared to a worn (thread 2mm) one

cantdecide wrote:

i appreciate anyone who tries to help

I believe you, many others wouldn't

cantdecide

JoeA3 wrote:

you still seem to have trouble grasping simple maths/physics

that hurts. the maths were never in dispute Joe. maybe you have trouble grasping basic English. the question is what's the best way of minimising hardness on an 18" wheel. the answer is not to get rid of the wheel because fundamentally the solution has to incorporate the wheel. otherwise it would be a different question, wouldn't it.

JoeA3

I give up! My english is ok, don't worry about that... but I'm sorry to say, there is no easy solution to your problem other than the ones repeatedly suggested to you. If you don't like those answers, I'm afraid there ain't much more we can do. My own car has 18" rims, and yes the ride is hard... there's nothing I can do about it other than downsize the wheels, but for me their appearance is worth the bumpy ride.

unkel

JoeA3 wrote:

My own car has 18" rims

Same here

JoeA3 wrote:

there's nothing I can do about it other than downsize the wheels, but for me their appearance is worth the bumpy ride.

When I bought my car and complimented the previous owner with the great look of it and particularly its low stance on those big wheels, he sighed that he wished sometimes that the wheels were just standard 16". I didn't understand him then. I do now although I've been lucky enough only to burst one tyre in over three years

Eoin

unkel wrote:

Same here



When I bought my car and complimented the previous owner with the great look of it and particularly its low stance on those big wheels, he sighed that he wished sometimes that the wheels were just standard 16". I didn't understand him then. I do now although I've been lucky enough only to burst one tyre in over three years

I had 16"s as standard when I got the car, and put on 18" wheels plus Eibach Pro lowering springs, and I certainly feel every bump in the road. I don't really regret it though, as anything less than an 18" wheel doesn't seem to fill out the arches at all.

Bluehair

What everyone is skirting around spelling out is the fact that there is little or no difference between identically sized tyres in terms of comfort, i.e. looking for a tyre with, say, a softer overall compound will have a negligable (and probably unnoticable) effect on comfort.

Bearing in mind the chassis, suspension, alignment etc has been setup from factory with a certain tyre size in mind i'd be very wary about just lashing on a tyre with a bigger sidewall.

Perhaps check around a few lexus specific forums and see if anyone has attempted the same thing? Let us know the results if you do this..

(For what it's worth i know someone who attempted the same thing on an e46 3-series, it wrecked the acceleration and handling was definitely compromised).