Economy VS Tire size

[steve1961]

A few interesting observations over 1000ks
I fitted a set of 275x75x16 Cooper ST maxx's and i found a few interesting things , one fuel economy has only marginally decreased on country trips up from 8.8 LPHK to 9.2 LPHK, so not unhappy about that , but city driving is a totally different story , now up to 11.2 LPHK , and today on a trip to Horsham driving into a head wind was 12 LPHK , the return was back to normal ,
the tires iam very happy with , their as quiet as the factory fitted " at's lol " ie highway tires , dry grip is awesome , and wet grip as good or better then the factory tires , so 1200 ks in 2 days , so far very happy , and i was expecting the fuel difference , but not as much in city driving , So my awesome fuel economy will take another hit next week with the bash plates and long range tank being fitted

 

[happy john]

Steve your getting nearly exactly the same as my mates 2010 k/cab with the same tyres he also lost a little grunt to boot.

 

[steve1961]

Steve your getting nearly exactly the same as my mates 2010 k/cab with the same tyres he also lost a little grunt to boot.

It was with a little trepidation , waiting to see what would happen , we can think ourselves lucky in respect of the Nissan stock tires being 255 , the difference is not all that much , when i had my ML Triton the std factory tires were only 245 , so the jump to 265 took a monster hit on economy

 

[TUFFD40]

that sucks that its drinking a lot more... I just went from standard to 265 70 16 marginally bigger for that reason as all my driving is in the city these day would of loved tyres your size

 

[Nakkers]

Did you put steel rims on ? wheres the pics?

 

[big zetor]

The exact same thing happened with mine, went from 8.9 t0 9.5 per 100ks and around town was 10.5 t0 11.5. now running 285's and it's gone up to 11.5 to 12.5 per 100ks. still pretty good i recken.

 

[steve1961]

Did you put steel rims on ? wheres the pics?

In my build thread , and no i got another set of factory alloys and had them acid stripped and powder coated black

 

[Nakkers]

Are yes looks good, I did check your garage first LOL.

 

[Old.Tony]

That sort of behaviour is completely expected. Larger tyres mean a larger lever from the axle to the road surface - it's harder to turn over. Once you're cruising at the sweet spot you might find it using slightly less fuel, but to get the thing up to speed takes more effort so it will use more fuel to do it.

It's all to do with gearing. If you want much bigger tyres with similar performance, calculate the %increase in tyre size and go that much lower in front and rear diff ratios = same final drive ratio as standard with the benefit of having your ass higher off the ground.

 

[grasshopper]

Old Tony,
That sounds good in theory, but the costs of changing diff ratios too = mucho denero.
Even longer then to save the costs in better fuel economy.

 

[rabbit-chop]

id imagine wind drag and road friction would play a big part too. especially with big mud tyres.

 

[happy john]

The larger tyres always rob you of power and economy my 89 d21 all 59kw was fitted with 33's and was great in sand and mud but used more fuel than a alco and was slow as a turtle but the thing would crawl anyplace without a fuss.

The td27 had the same size tank as now 75ltrs stock i would get 350kms per half tank stock when the wheels and tyres went on 280 was normal these days i always get 400-420 at half tank in my 22 but i have kept the tyres at 265-70 as i tow all the time no serious 4wd the zordo efs lift looks after the rest.

 

[steve1961]

Iam not unhappy , and was expecting it , was just more of an information post for others considering tyre sizes

 

[grasshopper]

At the moment, I am looking for tyres with the same O.D. to keep the same revs at 60, 80 and 100 Ks /hr.
If i went a size bigger then I could easily be in the cruddy 2000 rpm off boost vibration range.

 

[Old.Tony]

Old Tony,
That sounds good in theory, but the costs of changing diff ratios too = mucho denero.
Even longer then to save the costs in better fuel economy.

Absolutely right - but if you've a yen for the larger tyres AND lockers, you could do both at once - but otherwise, expect the change in performance.

 

[happy john]

I think we all have to ask our self do we need bigger tyres ect if i drive 90% of the time on the road why do i have a 285 muddie. Most atr's are better than the highway tyres fitted on wet tar and perform well in most situations.

I found that when i stupidly ran muddies the fuel bill was huge the noise drove me mad and in soft sand once you started spinning it would dig to China. In the 50k those tyres lasted i only went in bad mud twice.

At the moment i am running dueler 697 the new pattern all i can say is bloody good in the wet done 8k no wear and great in the sand let down it bellows nice and being a l/t tyre the sidewalls are strong less prone to staking.

But mud forget it a bfg atr will eat it for breakfast it picks up every little stone and slots into it's large grove and click clacks untill it dislodges and hits your paint i find they are great in anything bar mud only reason i got them was a cancelled order $210 each next time will be the bfg's.

 

[mitch92]

Will be interesting to see what my fuel
Is like when I drop from 265/70 to 245/75